Fixes to address 'deprecated conversion from string constant to char*' warnings with GCC
removing old GPU unit tests
Add more shapes to collision model ShapeType enum
use int instead of ShapeType type to be more consistent
Add new assets and geometry shapes
Merge branch 'develop' of https://github.com/projectchrono/chrono into develop
added two more actuator modes, can be be set by running m_act->Set_actuator_mode(0,1 or 2), for displacement, velocity or force linear actuation