Please add confirmation for glcean!!!!

[wenjoy]

I just ruined all my work of this afternoon with this command!!!!
It's a dangerous command to clean all your working tree and staged file, but its name looks like a git clean.

[jhillyerd]

Perhaps we should move gclean to gclean! and make gclean an abbreviation for the regular git clean, I agree that would be surprising.

[wenjoy]

I'd like to have a try.