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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/piloswine.asm

@@ -0,0 +1,10 @@
+; PiloswinePokedexEntry: ; 0x1d0c01
+	db "SWINE@" ; species name
+	dw 307, 1230 ; height, weight
+
+	db   "Although its legs"
+	next "are short, its"
+	next "rugged hooves"
+	page "prevent it from"
+	next "slipping, even on"
+	next "icy ground.@"