Disable access to Settings dialogue except on home screen

[ieatlint]

At present, on non-Symbian platforms, it is possible to access the Settings page without being on the home screen.

This in theory should not break anything, however some modifications to settings will not take effect until the audio recording is stopped and restarted. Additionally, the "back" button on the settings page will be incorrectly labeled if the audio device is capturing.

I need to remove the QAction that gives access to the dialogue except on the home screen, or work with it to allow adjusting [some] settings without restarting the audio device.