Added gl-platform module.

This will replace our GLInclude.h header file.
Updated all header files to include CPM's gl-platform.
Remove unused GLInclude.h header file.

This header file has been replace by GLPlatform.
Switching to CPM batch testing environment.

Need to add ghost repos to CPM in order to get this to work.
Update source_dir repo with ghost repo.
All tests now pass using modular batch testing.
Remove 3rdParty code made unnecessary by CPM.
Removing USE_SCIRUN_INTERFACE code.

SCIRun no longer has an external interface.
Remove GLM_SWIZZLE. That is defined for us automatically.