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/pinsir.asm

@@ -0,0 +1,10 @@
+; PinsirPokedexEntry: ; 0x1b99fb
+	db "STAGBEETLE@" ; species name
+	dw 411, 1210 ; height, weight
+
+	db   "When the tempera-"
+	next "ture drops at"
+	next "night, it sleeps"
+	page "on treetops or"
+	next "among roots where"
+	next "it is well hidden.@"