Moving carbon/middleclickon() form carbon.dm to click.dm and centralising it (there was two carbon/middleclickon() proc.
Moving carbon/altclickon() to click.dm as well.
Merge branch 'master' of https://github.com/tgstation/-tg-station into StingMiddleClickRuntimeFIx

Conflicts:
	code/modules/mob/living/carbon/carbon.dm
Merge pull request #5735 from phil235/StingMiddleClickRuntimeFIx

Moving carbon/middleclickon() form carbon.dm to click.dm