title: Update option (of Make file) in CMake
body: <p><br><br>
  I have a big project that uses CMake to create Make file. Sometimes, I add one small project and then have to run the CMake script for whole project (like delete previous, and create newer CMake with this project included). <br>
  I was wondering, whehter there is some option in CMake whereby I can only "update" the Make script (created by CMake) to include newly added project (rather than above option). <br><br>
  Thanks,</p>