Split items/ and trainers/ into their data/ and engine/ components

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/zapdos.asm

@@ -0,0 +1,10 @@
+; ZapdosPokedexEntry: ; 0x1cc697
+	db "ELECTRIC@" ; species name
+	dw 503, 1160 ; height, weight
+
+	db   "Legendary bird"
+	next "#MON. They say"
+	next "lightning caused"
+	page "by the flapping of"
+	next "its wings causes"
+	next "summer storms.@"