Resend engine-defined options after reuse=0 reload

Resend engine-defined options after reuse=0 reload

When the engine process is re-spawned for a new game under -xreuse setting,
any alteration of engine settings brought about through the Engine Settings
dialogs would be lost, and revert to the engine's default. This is now fixed
by re-sending all options (known from the previous load of the same engine)
with the current settings immediately after "protover 2", and ignoring the
engine's option features. Rather than clearing the option list, and
redefining it from the option features.