#672 Add estimated frame rate to status bar

[Simon Murphy]

Estimated frame rate seems to be available if you "Show info on the OSD" but it would be useful to have it on the status bar. When you "Show info" you get a full screen of stuff which completely covers the picture.

Currently if you enable "Video info" on the status bar it shows only FPS not estimated FPS. FPS might be fixed at 29.97 whereas estimated FPS can change and is useful for sources that change from 29.970 to 23.976 and back, potentially multiple times. The status bar is less instrusive than the full picture overlay.