Add comment shortcut (gcc)

[jrwrigh]

Summary

A really helpful vim shortcut to use would be using gcc to toggle the comment of a line.

I can't think it'd be that difficult to do either. Some simple if statements to chose whether to run I# or Idf# in the case of Python's comments.

[lambdalisue]

Vim itself does not provide such mapping. So it should be done by user as a custom binding.