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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/noctowl.asm

@@ -0,0 +1,10 @@
+; NoctowlPokedexEntry: ; 0x1cceb9
+	db "OWL@" ; species name
+	dw 503, 900 ; height, weight
+
+	db   "Its extremely soft"
+	next "feathers make no"
+	next "sound in flight."
+	page "It silently sneaks"
+	next "up on prey without"
+	next "being detected.@"