Plugin does not detect multiple connections on Windows reliably

[jason-watkins]

2790f55 makes changes to the Java client specifically designed to ensure that each instance of the XPlaneConnect class is recognized as a new connection by the plugin. This works as expected on Mac, but does not appear to work on Windows. On Windows, all requests are logged by the plugin as coming from connection 1.

Need to do some legwork to establish whether this bug affects the C and MATLAB clients as well, and find the root cause of the bug.

[jason-watkins]

The connection tracking code is significantly revamped in the next version (currently living here). The new code directly uses the binary representation of the client's address and port.