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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/delibird.asm

@@ -0,0 +1,10 @@
+; DelibirdPokedexEntry: ; 0x1d0db1
+	db "DELIVERY@" ; species name
+	dw 211, 350 ; height, weight
+
+	db   "It always carries"
+	next "its food with it,"
+	next "wherever it goes."
+	page "If attacked, it"
+	next "throws its food at"
+	next "the opponent.@"