installer maintenance

• Fix #31 (closed)
• Fix Core#149 (closed)
• Add a couple of scripts for convenience:
  • quick to compile from anywhere in a reasonably compact way
  • ./status.sh to get a quick overview of the difference between the local repo and the remote (useful for #15)
• tools/setup.sh now automatically fetches the new commits on the remote master branch (but let the user merge)
• Update CMake instruction for TUnfold