Implement switching tabs using Alt modifier + number #788
Description
Being able to switch tabs in the Main Window interface using keyboard shortcuts (eg Alt+1, Alt+2, etc) would be useful.
@innermous has implemented it in 11558a8 & 45e17c9.
Just to be careful, before merging that into 3.9.1 we should test the result under both Windows and OSX to ensure we're not conflicting with existing key bindings.