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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/alakazam.asm

@@ -0,0 +1,10 @@
+; AlakazamPokedexEntry: ; 0x1b8000
+	db "PSI@" ; species name
+	dw 411, 1060 ; height, weight
+
+	db   "It has an IQ of"
+	next "5000. It calcu-"
+	next "lates many things"
+	page "in order to gain"
+	next "the edge in every"
+	next "battle.@"