Get rid of globals.asm. Use ::s to export labels between objects.

globals.asm was a hack that:
- gave rgbasm an extra 100k lines to read
- increased reliance on the python preprocessor
- made the makefile a mess
- gave object creation an extra step
- wasn't even necessary

This speeds up build time by at least a third.

text/maps/cinnabar_mart.asm

@@ -1,10 +1,10 @@
-_CinnabarMartText2: ; a139b (28:539b)
+_CinnabarMartText2:: ; a139b (28:539b)
 	text "Don't they have X"
 	line "ATTACK? It's good"
 	cont "for battles!"
 	done
 
-_CinnabarMartText3: ; a13cb (28:53cb)
+_CinnabarMartText3:: ; a13cb (28:53cb)
 	text "It never hurts to"
 	line "have extra items!"
 	done