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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/remoraid.asm

@@ -0,0 +1,10 @@
+; RemoraidPokedexEntry: ; 0x1d0cd3
+	db "JET@" ; species name
+	dw 200, 260 ; height, weight
+
+	db   "To escape from an"
+	next "attacker, it may"
+	next "shoot water out of"
+	page "its mouth, then"
+	next "use that force to"
+	next "swim backward.@"