MCUs like the ESP32 can be reset if the serial port DTR line is
pulsed for a short time. You could just type CTRL-t d CTRL-t d
but that's a little awkward since you have to lift your finger
off the CTRL key to type the Ds. Now you can just type CTRL-T D.
* Added new command "D" to pulse the DTR line. I.E. Toggle its
state twice with a configurable duration between toggles.
* Added new config/command line option "--dtr-pulse-duration"
to set the duration between the DTR state toggles. The default
is 100ms.
Rework the color option to support setting ANSI color code values
ranging from 0..255 or "none" for no color or "list" to print a list of
available ANSI colors codes.
Also, disables color when piping.
Optional arguments, as parsed by the getopt_long mechanism, are
inherently inconsistent with how you define required arguments.
To avoid confusion we decide to avoid this inconsistency by replacing
optional options with additional options with required argmuments.
Also changes default timestamp format from ISO8601 to classic 24-hour
format as this is assumed to be the format that most users would prefer.
And reintroduces strict but optional ISO8601 format.
This feature allows to easily add more timestamp formats in the future.