#168 Add hotkeys (Options dialog, context menu), make them work properly

[R Kh]

I added shortcuts to the en_US language file (see attachment), and most of them work, but unfortunately, not all of them. The labels that should give focus to a text box, spin box or a drop-down list (combo box?) activate the wrong control (see attached screenshot).

It would be nice to integrate the hotkeys into the default language and to fix the navigation issue.