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

Move some data into a pokemon/ subdirectory

data/pokemon/dex_entries/starmie.asm

@@ -0,0 +1,10 @@
+; StarmiePokedexEntry: ; 0x1b9776
+	db "MYSTERIOUS@" ; species name
+	dw 307, 1760 ; height, weight
+
+	db   "It is said that it"
+	next "uses the seven-"
+	next "colored core of"
+	page "its body to send"
+	next "electric waves"
+	next "into outer space.@"