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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/pineco.asm

@@ -0,0 +1,10 @@
+; PinecoPokedexEntry: ; 0x1d04b0
+	db "BAGWORM@" ; species name
+	dw 200, 160 ; height, weight
+
+	db   "It spits out a"
+	next "fluid that it uses"
+	next "to glue tree bark"
+	page "to its body. The"
+	next "fluid hardens when"
+	next "it touches air.@"