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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/moltres.asm

@@ -0,0 +1,10 @@
+; MoltresPokedexEntry: ; 0x1cc706
+	db "FLAME@" ; species name
+	dw 607, 1320 ; height, weight
+
+	db   "Legendary bird"
+	next "#MON. It is"
+	next "said to migrate"
+	page "from the south"
+	next "along with the"
+	next "spring.@"