Fixed a slew of foriegn key import problems. #29

Curse's type_id was 0, which is bogus; this has been fixed by creating a
real ????? type.
Fourth-gen moves all had zero as a contest effect id, which was also
bogus.
Pokémon 494 and 495 were junk and have been scrapped entirely.
pokemon_form_groups's description column was too short.

pokedex's connect() now takes kwargs passed to sessionmaker().

A more major change: some tables, like pokemon, are self-referential and
contain rows that refer to rows later in the table (for example, Pikachu
evolves from Pichu, which has a higher id).  At the moment such a row is
loaded, the foreign key is thus bogus.  I solved this by turning on
autocommit and wrapping add() in a try block, then attempting to readd
every failed row again after the rest of the table is finished.  Slows
the import down a bit, but makes it work perfectly with foreign key
checks on.

pokedex/db/tables.py

@@ -176,7 +176,7 @@ class Move(TableBase):
     effect_id = Column(Integer, ForeignKey('move_effects.id'), nullable=False)
     effect_chance = Column(Integer)
     contest_type = Column(Unicode(8), nullable=False)
-    contest_effect_id = Column(Integer, ForeignKey('contest_effects.id'), nullable=False)
+    contest_effect_id = Column(Integer, ForeignKey('contest_effects.id'), nullable=True)
     super_contest_effect_id = Column(Integer, nullable=False)
 
 class Pokemon(TableBase):
@@ -270,7 +270,7 @@ class PokemonFlavorText(TableBase):
 class PokemonFormGroup(TableBase):
     __tablename__ = 'pokemon_form_groups'
     pokemon_id = Column(Integer, ForeignKey('pokemon.id'), primary_key=True, nullable=False, autoincrement=False)
-    description = Column(Unicode(255), nullable=False)
+    description = Column(Unicode(512), nullable=False)
 
 class PokemonFormSprite(TableBase):
     __tablename__ = 'pokemon_form_sprites'