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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/ampharos.asm

@@ -0,0 +1,10 @@
+; AmpharosPokedexEntry: ; 0x1cd626
+	db "LIGHT@" ; species name
+	dw 407, 1360 ; height, weight
+
+	db   "When it gets dark,"
+	next "the light from its"
+	next "bright, shiny tail"
+	page "can be seen from"
+	next "far away on the"
+	next "ocean's surface.@"