Fix #614 Add video scaling options

Freeseer now supports converting video signals from one display
resolution to another. Technically we already supported this, but there
were no scaling options so it wasn't very useful.

The following scaling options are now available when recording video:

- No scaling
- 240p (320x240)
- 360p (480x360)
- 480p (640x480)
- 720p (1280x720)
- 1080p (1920x1080)
Added "View Log" option to help menu; Empty log window
Changed log window size; Window no longer modal
Added Log table view and model; Created custom handler to populate
the model. Added clear button functionality.
Improved LogHandler constructor, code readability, and added level check
Removed redundant code
Fixed code based on comments
Added latest high priority message to status bar.
Changed logical flow of log.
Added option to filter log based on level.
Reverted to old logical flow with multiple listeners.
Fixed copyright years
Removed "All" option; Items no longer editable; Replaced grid;
Made horizontal header unclickable; Hid vertical header
Added/improved docstrings. Don't ignore log messages based on level.
Fixed docstrings and naming
Full module name in log with different column sizes
Customized slider for level selection; Colored level labels
Switched to using permanent widget instead of status bar itsefl
Added new state icons
Updated resource file
Changed icons
Updated resource file