Improve Morse decoding

[leskerr]

PyKOB's decoding algorithm automatically adapts to the speed of the incoming Morse. Sometimes this does not work as well as MorseKOB 2.5's simpler, fixed speed approach.

Either PyKOB's decoding algorithm needs to be improved so as to provide equal or better performance, or there should be an option whereby the user can disable the adaptive feature.

[AESilky]

Maybe also a keyboard key that will put it back to the set value. I realize that bumping the speed up or down a notch will set it, but an easy keyboard key that will just set it back to the currently configured value might be good.