adds mnemonics to view switcher

This adds mnemonics (also known as Access Keys) to the view switcher, which makes it easier to navigate the application with only a keyboard. Just makes it so holding Alt highlights the first character of each button's title, and pressing the corresponding character will then switch to the desired view. i.e. Alt + I for the IP view.

I'm not sure if this was the best way to implement it so, please, do tell me if there are any improvements that can be made :).

Also, since this alters translatable strings, some adaptions are required in the translations. I can also go ahead and adapt some of those if desired.