Link ids were being used interchangeably with the mavlink channel for
the link. Link ids handed out as a numerically increasing integer. Once
the counter went past MAVLINK_COMM_NUM_BUFFERS all hell would break
loose and cause memory corruption.

Also many LinkManager API changes to further isolate all link
management inside LinkManager.

This is the Pixhawk research board, not the PX4 production board.

This removes double emit of signals.

This api doesn’t make any sense given the fact that LinkInterface
signals bytesReceived with the bytes in the signal. Also the reason why
it is never called!

Converted LinkInterface from a pure-virtual interface into an abstract base class. This centralized the data rate calculation code for all subclasses. Also added the necessary code to provide upstream/downstream data rate calculations for all LinkInterface-derived classes.

Renamed getNominalDataRate to getConnectionSpeed. Also added upstream/downstream data rate functions to all Link classes.

Removed LinkInterface methods which were never being called. Updated various LinkInterface implementation classes to remove the methods. Some methods such as the ones which measure data rates or bits sent/received were implemented in only some of the implementation classes, and in some cases implemented incorrectly. If they were called, the values returned would be incorrect. Although there was some partial implementation for these I removed them as well since in all case they were never being called by any code. In checking Blame, these came across in 2010 and have remained unimplemented since them, so I figure better to clean up than leave crufty, unused, half finished stuff in.

Have settings loaded/stored correctly for all joysticks based on their UAS type and autopilot type. Switching between UASes doesn't work right yet, however.

Changed many functions in the abstract *Link classes to be const. This facilitates setting other functions as const. The metadata for specific links are reset when the links are added.

Partway through refactoring of UAS deletion. This is in order to actually support removing UASes from QGC, which is currently impossible.

Changed many functions in the abstract *Link classes to be const. This facilitates setting other functions as const. The metadata for specific links are reset when the links are added.

Partway through refactoring of UAS deletion. This is in order to actually support removing UASes from QGC, which is currently impossible.

Introduced persistence in RGBDview, needs debugging, fixed a bug in param reading in the simulator, pushed message sender a bit forward, not working yet