Improve table docs w.r.t. ids and game indices.

Went though the table docs and noted which tables have ids that correspond
to game ids, and explained why we sometimes have ids in the 10000s.

Since docs attached to id columns aren't displayed in the web documentation,
these edits all go in the class docstring, and i took the liberty of deleting
the id column docs from every table i touched.

Also: added some words about how to get to the species from pokemon and
pokemon_form.

Also: note that item flags are not official (they are a holdover from
brownkun) and item pockets are sort of kind of official (they originated from
D/P i believe, but i'm not sure how we've been assigning them for newer items).

Pertains to #99.

pokedex/db/tables.py

@@ -114,11 +114,14 @@ create_translation_table('language_names', Language, 'names',
 ### The actual tables
 
 class Ability(TableBase):
-    u"""An ability a Pokémon can have, such as Static or Pressure."""
+    u"""An ability a Pokémon can have, such as Static or Pressure.
+
+    IDs below 10000 match the internal ID in the games.
+    IDs above 10000 are reserved for Conquest-only abilities.
+    """
     __tablename__ = 'abilities'
     __singlename__ = 'ability'
-    id = Column(Integer, primary_key=True, nullable=False,
-        doc=u"This ability's unique ID; matches the games' internal ID")
+    id = Column(Integer, primary_key=True, nullable=False)
     identifier = Column(Unicode(79), nullable=False,
         doc=u"An identifier",
         info=dict(format='identifier'))
@@ -176,10 +179,11 @@ class Berry(TableBase):
     u"""A Berry, consumable item that grows on trees.
 
     For data common to all items, such as the name, see the corresponding item entry.
+
+    ID matches the in-game berry number.
     """
     __tablename__ = 'berries'
-    id = Column(Integer, primary_key=True, nullable=False,
-        doc=u"This Berry's in-game number")
+    id = Column(Integer, primary_key=True, nullable=False)
     item_id = Column(Integer, ForeignKey('items.id'), nullable=False,
         doc=u"The ID of the item that represents this Berry")
     firmness_id = Column(Integer, ForeignKey('berry_firmness.id'), nullable=False,
@@ -713,12 +717,18 @@ create_translation_table('contest_type_names', ContestType, 'names',
 class EggGroup(TableBase):
     u"""An Egg group. Usually, two Pokémon can breed if they share an Egg Group.
 
-    (exceptions are the Ditto and No Eggs groups)
+    Exceptions:
+
+    Pokémon in the No Eggs group cannot breed.
+
+    Pokemon in the Ditto group can breed with any pokemon
+    except those in the Ditto or No Eggs groups.
+
+    ID matches to the internal ID used in the games.
     """
     __tablename__ = 'egg_groups'
     __singlename__ = 'egg_group'
-    id = Column(Integer, primary_key=True, nullable=False,
-        doc=u"A unique ID for this group")
+    id = Column(Integer, primary_key=True, nullable=False)
     identifier = Column(Unicode(79), nullable=False,
         doc=u"An identifier.",
         info=dict(format='identifier'))
@@ -937,11 +947,13 @@ create_translation_table('growth_rate_prose', GrowthRate, 'prose',
 )
 
 class Item(TableBase):
-    u"""An Item from the games, like "Poké Ball" or "Bicycle". """
+    u"""An Item from the games, like "Poké Ball" or "Bicycle".
+
+    IDs do not mean anything; see ItemGameIndex for the IDs used in the games.
+    """
     __tablename__ = 'items'
     __singlename__ = 'item'
-    id = Column(Integer, primary_key=True, nullable=False,
-        doc=u"A numeric ID")
+    id = Column(Integer, primary_key=True, nullable=False)
     identifier = Column(Unicode(79), nullable=False,
         doc=u"An identifier",
         info=dict(format='identifier'))
@@ -980,7 +992,7 @@ create_translation_table('item_flavor_summaries', Item, 'flavor_summaries',
 )
 
 class ItemCategory(TableBase):
-    u"""An item category. Not official."""
+    u"""An item category.  Not official."""
     __tablename__ = 'item_categories'
     __singlename__ = 'item_category'
     id = Column(Integer, primary_key=True, nullable=False,
@@ -999,7 +1011,7 @@ create_translation_table('item_category_prose', ItemCategory, 'prose',
 )
 
 class ItemFlag(TableBase):
-    u"""An item attribute such as "consumable" or "holdable". """
+    u"""An item attribute such as "consumable" or "holdable".  Not official. """
     __tablename__ = 'item_flags'
     __singlename__ = 'item_flag'
     id = Column(Integer, primary_key=True, nullable=False,
@@ -1064,7 +1076,7 @@ class ItemGameIndex(TableBase):
         doc=u"Internal ID of the item in the generation")
 
 class ItemPocket(TableBase):
-    u"""A pocket that categorizes items."""
+    u"""A pocket that categorizes items.  Semi-offical."""
     __tablename__ = 'item_pockets'
     __singlename__ = 'item_pocket'
     id = Column(Integer, primary_key=True, nullable=False,
@@ -1165,11 +1177,13 @@ class Machine(TableBase):
         return self.machine_number >= 100
 
 class Move(TableBase):
-    u"""A Move: technique or attack a Pokémon can learn to use."""
+    u"""A Move: technique or attack a Pokémon can learn to use.
+
+    IDs below 10000 match the internal IDs used in the games.
+    IDs above 10000 are reserved for Shadow moves from Colosseum and XD."""
     __tablename__ = 'moves'
     __singlename__ = 'move'
-    id = Column(Integer, primary_key=True, nullable=False,
-        doc=u"A numeric ID")
+    id = Column(Integer, primary_key=True, nullable=False)
     identifier = Column(Unicode(79), nullable=False,
         doc=u"An identifier",
         info=dict(format='identifier'))
@@ -1603,11 +1617,13 @@ class Pokemon(TableBase):
     different types, moves, or other game-changing properties counts as a
     different Pokémon.  For example, this table contains four rows for Deoxys,
     but only one for Unown.
+
+    Non-default forms have IDs above 10000.
+    IDs below 10000 match the species_id column, for convenience.
     """
     __tablename__ = 'pokemon'
     __singlename__ = 'pokemon'
-    id = Column(Integer, primary_key=True, nullable=False,
-        doc=u"A numeric ID")
+    id = Column(Integer, primary_key=True, nullable=False)
     identifier = Column(Unicode(79), nullable=False,
         doc=u'An identifier, including form iff this row corresponds to a single, named form',
         info=dict(format='identifier'))
@@ -1789,11 +1805,15 @@ class PokemonForm(TableBase):
     color differences) of every Pokémon, regardless of how the games treat
     them.  Even Pokémon with no alternate forms have one row in this table, to
     represent their lone "normal" form.
+
+    Forms which are not the default for their species have IDs above 10000.
+    IDs below 10000 correspond to ID of the species for convenience,
+    but this should not be relied upon.
+    To get the species ID of a form, join with the pokemon table.
     """
     __tablename__ = 'pokemon_forms'
     __singlename__ = 'pokemon_form'
-    id = Column(Integer, primary_key=True, nullable=False,
-        doc=u'A unique ID for this form.')
+    id = Column(Integer, primary_key=True, nullable=False)
     identifier = Column(Unicode(79), nullable=False,
         doc=u"A unique identifier for this form among all forms of all Pokémon",
         info=dict(format='identifier'))
@@ -1960,11 +1980,13 @@ create_translation_table('pokemon_shape_prose', PokemonShape, 'prose',
 )
 
 class PokemonSpecies(TableBase):
-    u"""A Pokémon species: the standard 1–151.  Or 649.  Whatever. """
+    u"""A Pokémon species: the standard 1–151.  Or 649.  Whatever.
+
+    ID matches the National Pokédex number of the species.
+    """
     __tablename__ = 'pokemon_species'
     __singlename__ = 'pokemon_species'
-    id = Column(Integer, primary_key=True, nullable=False,
-        doc=u"A numeric ID")
+    id = Column(Integer, primary_key=True, nullable=False)
     identifier = Column(Unicode(79), nullable=False,
         doc=u"An identifier",
         info=dict(format='identifier'))