Removed LinkInterface methods which were never being called. Updated var...

...ious 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.

FYI: I'm cleaning these up because I have two other changes locally I want to get through. The first is to rewrite SerialLink to use Signals instead of a forever thread type implementation. No reason to be written this way. QSerialPort support readyReady type signaling. Gets rid of a lot of the SerialLink code which basically duplicates the internals of qserialport. Following that I have changes which I call AutoLink which will automatically find the connection to the board by connecting to ports and watching for a MAVLink protocol. This makes it much easier to move between USB connected board, Radio Link, HIL or SITL without having to remember all the various settings constantly changing things. You just git connect and it will find it for you.