* Add Linux openvdb integration
* Add Mac openvdb integration and enable in ALL
* Create openvdb sandbox to test integration.
* Additional fixes in the patches
* Remove slabasebed sandbox as it has no relevance now
* Provide FindOpenVDB module and fix build issues
* Remove unused libnest2d files. Make it use the global build script targets.
* Modify FindTBB to address multi-config builds and take care of __TBB_NO_IMPLICIT_LINKAGE
* Move FindNLopt to project common cmake module dir
* Rename libnest.hpp to nester.hpp and libnest.h to libnest.hpp
* Clean up common test suite build scripts