add shortcut Ctrl+Tab and Ctrl+Shift+Tab

[pedro-nonfree]

Tabs traversing with the keyboard are pretty generic on firefox, chrome, etc. and I was expecting to work in this (nice!) application. They are very useful to avoid using the mouse to click and traverse through different messages on different platforms

[manusa]

Yep, this one should be easy to implement. I'll try to add it to the upcoming release.

Thx for your feedback.

[manusa]

I'm implementing this as ctrl+tab and shift+ctrl+tab for every platform, including macOS (maybe this convention assumption is wrong).

[pedro-nonfree]

thank you @manusa tried it on v0.0.83 and it works great :heart: