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/machamp.asm

@@ -0,0 +1,10 @@
+; MachampPokedexEntry: ; 0x1b8133
+	db "SUPERPOWER@" ; species name
+	dw 503, 2870 ; height, weight
+
+	db   "With four arms"
+	next "that react more"
+	next "quickly than it"
+	page "can think, it can"
+	next "execute many"
+	next "punches at once.@"