MKOB: Implement Keyer interface option

[leskerr]

And, for extra credit, implement the left and right arrow keys to be used as a simulated bug (or straight key).

[AESilky]

From: http://kob.sdf.org/morsekob/morsekob25/tutorial.htm

Has a built-in keyer (automatic dots and manual dashes) for use with paddles

I believe I've seen a slightly more detailed description, including schematic for the cable to connect one.
Can we include the description here.

I have physically seen a keyer and have watched videos of one being used, but I don't have one, so I would not be able to test.

[leskerr]

The keyer paddle connections are as follows:

Line	Pin	Function
DTR	4	Manual key or paddle common
DSR	6	Manual key or dot paddle
CTS	8	Dash paddle
RTS	7	Sounder output
SG	5	Sounder ground

You don't need an actual keyer paddle to test. Just connect pins 4 and 6 together and see if you get a string of dots. Connecting pins 4 and 8 should hold the circuit closed. Of course this won't work until the keyer function is added to pykob/kob.py