Channel Signal Strength

Adding a channel signal strength to the status bar that can be be turned on and off in the preferences. As a signal strength meter is very helpful for correct antenna positioning. As a rough estimation should be enough there's no need for displaying absolute level. Showing something like 'insufficient=red=0-60%', 'sufficient=yellow=60-90%', 'perfect=green=90-100%' would be sufficient for most users.

Added to main interface for discussion. It was decided a separate dialogue was really superfluous. Also added a check box on the edit main menu to turn it on/off (expected to only be used for inital hardware set up) It was placed above the main window as it seemed logical for it to be linked with the main video window.
[update] meters tried in main window but they cluttered them up a somewhat. After discussion it was decided that they were a tool and belonged as a dialogue window.