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/togepi.asm

@@ -0,0 +1,10 @@
+; TogepiPokedexEntry: ; 0x1cd396
+	db "SPIKE BALL@" ; species name
+	dw 100, 30 ; height, weight
+
+	db   "It is considered"
+	next "to be a symbol of"
+	next "good luck. Its"
+	page "shell is said to"
+	next "be filled with"
+	next "happiness.@"