Add sample screenclone-runx.
XFlush instead of XSync at a few places.
Clean up debugging.
Add optional tracing of X call durations.
Get rid of mixed tab/space indentation.
Link Xfixes and Xext.

closes #8
Don't crash when XFixesGetCursorImage returns NULL.
Enable/disable copying with SIGUSR1/SIGUSR2
Merge remote-tracking branch 'upstream/master'

Conflicts:
	Makefile
	screenclone.cc
Version 20130315.0