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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/eevee.asm

@@ -0,0 +1,10 @@
+; EeveePokedexEntry: ; 0x1cc1b2
+	db "EVOLUTION@" ; species name
+	dw 100, 140 ; height, weight
+
+	db   "Its ability to"
+	next "evolve into many"
+	next "forms allows it to"
+	page "adapt smoothly"
+	next "and perfectly to"
+	next "any environment.@"