Rename all files in data/pokedex/entries/

Some people suggested this would be a good idea, and make management of
the files easier. I'm inclined to agree.

data/pokedex/entries/bulbasaur.asm

@@ -0,0 +1,10 @@
+; BulbasaurPokedexEntry: ; 0x181695
+	db "SEED@" ; species name
+	dw 204, 150 ; height, weight
+
+	db   "While it is young,"
+	next "it uses the"
+	next "nutrients that are"
+	page "stored in the"
+	next "seeds on its back"
+	next "in order to grow.@"