Change maps to nnoremaps

[tpope]

I hope you'll agree this change is pretty benign, as my muscle memory for <C-c> to cancel out of visual mode (among other things) has been killing me (and might even be a deal breaker even with this fix).

Note the nore portion means "don't invoke maps recursively", which guards against the unlikely case that someone has remapped colon.

[spolu]

Thanks!