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/growlithe.asm

@@ -0,0 +1,10 @@
+; GrowlithePokedexEntry: ; 0x182eaa
+	db "PUPPY@" ; species name
+	dw 204, 420 ; height, weight
+
+	db   "It controls a big"
+	next "territory. If it"
+	next "detects an unknown"
+	page "smell, it roars"
+	next "loudly to force"
+	next "out the intruder.@"