Support multiple selection

[raould]

e.g. I'd like to get a list of SHAs for cherry picking on some other command line. I'd like to be able to select multiple rows of the repo history (menu View > History) and then right-click and copy their SHAs. That's one example, ideally most anything I can do with 1 selected line should be doable with N lines, except for those things that just can't make sense for more than 1 item 'natch.

[Feuermurmel]

Almost created a duplicate of this issue. My motivation for this feature would be to cherry-pick multiple commits or create an octopus merge with multiple commits.