- Improve speed in retrieving Histo in Spectra
        - Improve speed of Apply Calibration

* event

        - now use AGAUSS by default
        - add warning when wrong token is used

* fixing travis version of g4

- Adding travis build of G4
- Adding travis run of test
- fixing potential conflict when compiling and running nps on linux

        - Running Example 1 and 2 using reference root file (no sim
            needed)

- the issue is that root is not build with clang, and that cause a crash

  - linux
  - osx