Add option 'Floating Byoyomi'

Add option 'Floating Byoyomi'

In USI (-s) mode an option 'Floating Byoyomi' will be announced, which
will force the 'suffix' to the 'go' command to specify a byoyomi equal
to a reasonable time to think (timeLeft/40 + inc). This can be used as
a work-around to let engines that ignore the time left and always think
they are playing in byoyomi (a common misery in USI engines) work reasonably
well under incrementalor sudden-death TC. This then removes the need to
specify the suffix on the UCI2WB command line.