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/omanyte.asm

@@ -0,0 +1,10 @@
+; OmanytePokedexEntry: ; 0x1cc3c1
+	db "SPIRAL@" ; species name
+	dw 104, 170 ; height, weight
+
+	db   "In prehistoric"
+	next "times, it swam on"
+	next "the sea floor,"
+	page "eating plankton."
+	next "Its fossils are"
+	next "sometimes found.@"