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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/lanturn.asm

@@ -0,0 +1,10 @@
+; LanturnPokedexEntry: ; 0x1cd1de
+	db "LIGHT@" ; species name
+	dw 311, 500 ; height, weight
+
+	db   "This #MON uses"
+	next "the bright part of"
+	next "its body, which"
+	page "changed from a"
+	next "dorsal fin, to"
+	next "lure prey.@"