Improve key morse in ssb modulator

[internetuser22]

suggestion ability to manually key with a straight key, by com port or mouse

[f4exb]

These controls do exist: check under the "WPM" button (it is not in the main screenshot) Look at 16.7 to 16.10 under here https://github.com/f4exb/sdrangel/tree/master/plugins/channeltx/modssb#166-text-playstop

To use a hardware key you will need another program to be able to generate keystrokes moreover it should be able to produce sound feedback.

[f4exb]

It turns out that the easier way to interface a morse key to a computer is to recycle a mouse by connecting the right and left buttons to the iambic keys (for iambic) or just one of them for a straight key. Mouse control is not implemented and it would be a significant improvement in usability if it was.

More importantly a sound feedback should be linked to the keys. It is not possible to use the radio feedback because of the delay.

[f4exb]

With the present design of audio control it does not seem possible to avoid a slight delay on audio. So even when activating the audio feedback this delay is still annoying when keying directly with the mouse. Therefore I think a CW keyer with a buzzer for audio feedback is necessary while using the straight key mode in the SSB modulator. You can then sacrifice a USB mouse as demonstrated in this video: https://www.youtube.com/watch?v=q_STHEIT_i8