Add a read-only mode

[Alphare]

I don't want to accidentally do anything with a shortcut, I think a read-only mode (command line argument/config?) to remove all write actions would be super useful.

[vamolessa]

This is interesting. I think the only non-write commands are status, log and the diff/changes commands. So is it common to only want to see logs or diffs?

[Alphare]

I basically only want to see log, status, (p)diff, export, stack and topics. The rest I prefer to do with the Mercurial/Git CLI. :)