update to command wait mechanism and compiler warnings

The most significant change in this patchset relates to how a main calling application "waits" for a command to be completed. The wait state variables have been split in to their own class for clarity.

Building the jdksavdecc-c library with MSVC 2013 Express gives a cl "-Wextra" error, so it has been removed - it wasn't strictly required anyway as the avdecc-lib controller library compiles in the C sources it needs directly.