Add Mt. Moon Crater

The map functions and the ROM builds. It has no wild data, and nothing goes to it.

What's done;
- Map design, I think this is one of the best I've ever done, especially within these limits.
- Integration, set up a warp and you can go there, easy.

What's not done
- Wild data
- Fishing group
- Water mons
- Event signs
- Young Sada in Pewter Museum of Science

Very simple map to produce.

data/maps/objects/MtMoonCrater.asm

@@ -0,0 +1,12 @@
+MtMoonCrater_Object:
+	db $0 ; border block
+
+	def_warp_events
+	warp_event 23, 49, 0, LAST_MAP
+	warp_event 22, 49, 0, LAST_MAP
+
+	def_bg_events
+
+	def_object_events
+
+	def_warps_to MT_MOON_CRATER