Create a back button

[InterwebsGroup]

It would be awesome to have a back button like the browser version does so that you can get back and forth between issues without losing your place, since the breadcrumbs are not the greatest for that. It would also be really cool if you could use Mac touchpad gestures to go back and forth like a lot of the native apps have.

[aronprins]

I think touchpad gestures are a MUST and will add these.

An actual back/forth button is going to be tricky UI wise I think but I'll see what I can do!

[aronprins]

Closing this out since the swipe navigation support from PR #7 is now merged into master.