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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/quilava.asm

@@ -0,0 +1,10 @@
+; QuilavaPokedexEntry: ; 0x1ccb33
+	db "VOLCANO@" ; species name
+	dw 211, 420 ; height, weight
+
+	db   "Before battle, it"
+	next "turns its back on"
+	next "its opponent to"
+	page "demonstrate how"
+	next "ferociously its"
+	next "fire blazes.@"