Add C++ wrappers

[aaronjridley]

In order for this library to be used by C++ codes, like Aether, it needs to have wrappers with calls in C++:

• Create wrappers for all of the calls needed by the driver code
• Modify the Makefile to compile the C++ wrapper codes if desired
• Create test main code(s) that tests the functionality of the different calls (basically mimic all F90 tests)
• Write documentation that describes how to use the wrappers