Better fix of feature timeout

Better fix of feature timeout

The previous fix of the 2nd engine's done=1 aborting the 1st engine's
feature timeout by starting the game caused problems with v1 engines,
or other engines that would never send done=1. It is now fixed by
explicitly testing for a pending feature timeout after resurrecting
the 1st engine, rather than having TwoMachinesEventIfReady wait for
initDone to be set by reception of done=1.
 Also refrain from freezing the UI between match games, as in TwoMachines
mode the UI is mostly disabled anyway.