merge with master, include issue 109

COLLABORATION_AGREEMENT.md

CONTRIBUTING.md

Documentation/Examples/CMakeLists.txt

Documentation/Examples/cascade_example.cc

Environment/IMediumModel.h

Environment/NuclearComposition.h

Framework/Cascade/Cascade.h

Framework/Geometry/RootCoordinateSystem.h

Framework/Geometry/Trajectory.h

Framework/Geometry/Volume.h

Framework/Random/UniformRealDistribution.h

Framework/Utilities/Bit.h

Framework/Utilities/Singleton.h

GUIDELINES.md

Processes/CMakeLists.txt

Processes/Sibyll/Decay.h

Processes/Sibyll/Interaction.h

Processes/Sibyll/SibStack.h

Processes/Sibyll/sibyll2.3c.cc

Processes/Sibyll/sibyll2.3c.h