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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/kingler.asm

@@ -0,0 +1,10 @@
+; KinglerPokedexEntry: ; 0x1b8e45
+	db "PINCER@" ; species name
+	dw 403, 1320 ; height, weight
+
+	db   "Its oversized claw"
+	next "is very powerful,"
+	next "but when it's not"
+	page "in battle, the"
+	next "claw just gets in"
+	next "the way.@"