`mrhlpr checkout x` overrides unsaved changes

when calling git checkout, git will not checkout if it means it will loose modifications to the working directory:

> git checkout HEAD~100
error: Your local changes to the following files would be overwritten by checkout:
	channels.cfg
Please commit your changes or stash them before you switch branches.
Aborting

On the other hand, mrhlpr does continue anyway, and worse, it overwrites the modified files (reset --hard). Losing work is not fun.

Beside this "lost work" issue, I think the behavior of the checkout command should be consistent with git or the name should be changed. That would be in accordance to the principle of least surprise. IMO calling the current "checkout" command "review" (mrhlpr review 1234) would be much less surprising.