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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/aerodactyl.asm

@@ -0,0 +1,10 @@
+; AerodactylPokedexEntry: ; 0x1cc576
+	db "FOSSIL@" ; species name
+	dw 511, 1300 ; height, weight
+
+	db   "In prehistoric"
+	next "times, this"
+	next "#MON flew"
+	page "freely and"
+	next "fearlessly through"
+	next "the skies.@"