DVB: Add signal statistic to the status bar.

This commit fixes #899.
Move strings used in the status bar to resources.
Remove unused IDS_SCREENSHOT_ERROR_MADVR string from resources.
cosmetics
Disable some menus when it make sense to do so.
DVB: Disable pause for capture mode to avoid accidental playback stop.
We don't support time shifting yet.

This commit fixes #890.
Updated Polish translation.
apply astyle