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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/seaking.asm

@@ -0,0 +1,10 @@
+; SeakingPokedexEntry: ; 0x1b9690
+	db "GOLDFISH@" ; species name
+	dw 403, 860 ; height, weight
+
+	db   "When autumn comes,"
+	next "the males patrol"
+	next "the area around"
+	page "their nests in"
+	next "order to protect"
+	next "their offspring.@"