Fix resetting of terminal colors in the trace after a system call.

Previously it unconditionally emitted an ASCII escape code on UNIX, even
if use the stream didn't support colors.
Initialize the traceCycles member.
Merge branch 'master' into axe_json

Conflicts:
	lib/LoggingTracer.cpp
	tools/axe/Options.cpp
Force all instructions to yield for round-robin scheduling at the cost of performance