PortMedia Code

Worked on Doxygen comments and created new documentation directory.

Added doxygen output -- this needs some proofreading and refinement for formatting, but the info is all good.

Adding missing file to repo.

In CoreMIDI API, hide host error when closing an input when output is already shut down. It is considered correct to call Pm_Close() even if the sender no longer exists. This version passes all tests on macOS.

Fixed another CMake problem - flags for Linux Release.

forgot to remove print statement from debugging. This version fixes it and compiles Debug and Release versions on VS Community 2019.

Updates to CMakeLists for linux, added some event handling for port connect and disconnect, fixed virtual output to not appear also as input. All tests now pass on Linux.

to test fast on Windows, we need to specify an output buffer based on message rate. Also updated pm_test/README.txt based on running the tests on Windows

Took out some debugging print statements.

Output to virtual ports on macOS are rate limited in the same was as IAC Bus connections. This is implemented along with more options for testing with fast, fastrcv, and midithru. Tests are described in pm_test/README.txt.