First pass in getting rid of ChGlobals:

- use free function GetUniqueIntID()
- make DLL_CreateGlobals() and DLL_DeleteGlobals() do nothing.
- use ChTimer in demo_coords
Merge branch 'develop' into feature/irr_data
Remove ChApidll.{h,cpp} and all calls to DLL_CreateGlobals/DLL_DeleteGlobals.
Several fixes to mitsubaRender.cpp to reflect latest API changes.
Remove ChApidll.{h,cpp} and all calls to DLL_CreateGlobals/DLL_DeleteGlobals.

Note that many of these files are not included in the build!
Add global free functions for dealing with the Chrono data.

While this set of changes do not address the issue of where the data/ directory lives, they offer the following:
(1) it isolates the hard-coded default location (namely "../data"), relative to the location of the executable programs, to a single place (in ChGlobal.cpp)
(2) it allows external projects that depend on Chrono to access the default Chrono data files without having to copy the data/ directory.  Instead, simply invoke SetChronoDataPath() to specify where the Chrono data directory is (for example, in the Chrono source tree or the Chrono install tree)

The three new functions are as follows:
(1) SetChronoDataPath(): specifies the location of the Chrono data/ directory. The default is "../data/".  Note that this function is not thread-safe.
(2) GetChronoDataPath(): retrieves the location of the Chrono data/ directory (thread-safe)
(3) GetChronoDataFile(): obtains the complete filename given the name of a file or subdirectory relative to the location of the Chrono data directory (thread-safe)
Use GetChronoDataFile in all Irrlicht demos.
Merge branch 'develop' into feature/irr_data
Use `const char*` arguments.
Use GetChronoDataFile in demos.
Add function to specify starting point for the sequence of generated IDs.

This function can be used, for example, to ensure that consecutive runs will have different sequences of generated IDs.
Merge branch 'feature/irr_data' into develop