Added simple test for ctkHighPrecisionTimer.
Use MacOS specific functions for measuring time, issue #325.
Fix mac compilation by removing librt  Issue #325
Fixed duplicated symbol error due to definition in .h file, issue #325.
Merge remote-tracking branch 'origin/325-high-precision-timer-macos'

* origin/325-high-precision-timer-macos:
  Fixed duplicated symbol error due to definition in .h file, issue #325.
  Fix mac compilation by removing librt  Issue #325
  Use MacOS specific functions for measuring time, issue #325.
  Added simple test for ctkHighPrecisionTimer.
Fix for #325 to build on mac

Including the QtUiTools prefix to the include directive causes the compile
failure below, so this removes it.  Oddly, the QtXmlPatters prefix
did not cause a build error, but I remove it anyway to be consistent
with other uses of that header in the rest of the code.

[ 93%] Building CXX object Applications/ctkCommandLineModuleExplorer/CMakeFiles/ctkCommandLineModuleExplorer.dir/ctkCommandLineModuleExplorerMain.cpp.o
/Users/pieper/ctk/latest/CTK/Applications/ctkCommandLineModuleExplorer/ctkCommandLineModuleExplorerMain.cpp:33:10: fatal error: 'QtUiTools/QUiLoader' file not found
#include <QtUiTools/QUiLoader>
         ^
1 error generated.
make[2]: *** [Applications/ctkCommandLineModuleExplorer/CMakeFiles/ctkCommandLineModuleExplorer.dir/ctkCommandLineModuleExplorerMain.cpp.o] Error 1
make[1]: *** [Applications/ctkCommandLineModuleExplorer/CMakeFiles/ctkCommandLineModuleExplorer.dir/all] Error 2
make: *** [all] Error 2
Merge branch 'fix-macos-cmdlinemodule-explorer-errors'