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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/flareon.asm

@@ -0,0 +1,10 @@
+; FlareonPokedexEntry: ; 0x1cc2ec
+	db "FLAME@" ; species name
+	dw 211, 550 ; height, weight
+
+	db   "Once it has stored"
+	next "up enough heat,"
+	next "this #MON's"
+	page "body temperature"
+	next "can reach up to"
+	next "1700 degrees.@"