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/crobat.asm

@@ -0,0 +1,10 @@
+; CrobatPokedexEntry: ; 0x1cd0f5
+	db "BAT@" ; species name
+	dw 511, 1650 ; height, weight
+
+	db   "As a result of its"
+	next "pursuit of faster,"
+	next "yet more silent"
+	page "flight, a new set"
+	next "of wings grew on"
+	next "its hind legs.@"