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.
Fixed broken UnitTest build

Build files were broken for unit test. Seems to difficult to try to kep
qgroundcontrol.pro and qgcunittest.pro in sync with each other. Instead
I made qgcunittest.pro just include qgroundcontrol.pro. This required
some tweaks to allow TARGET to be set from the outside as well as to
leave out main.cc. Also needed to modify qgroundcontrol.pri to use
TARGET instead of hardcoding app name. This way it can build either
qgroundcontrol.pp or qgcunittest.app. At this point only works on osx.
Altitude splitted to altitudeAMSL and altitudeRelative, speed splitted to airSpeed and groundSpeed. PrimaryFlightDisplay uses airSpeed for FW and groundSpeed for MC.
Merge branch 'UnitTestFixes' of https://github.com/DonLakeFlyer/qgroundcontrol into UnitTestFixes

Conflicts:
	qgroundcontrol.pri
Comment change
Fix AutoTest build breaks
Make qgroundcontrol.pri agnostic to app name

Use TARGET instead of hardcoded qgroundcontrol.app name. This allows
this file to build unit test app as well as qgroundcontrol app.
Fixed UnitTest code and bugs found by unit tests
Can't spell
Merge pull request #434 from Susurrus/exposeSysTime

Expose SYSTEM_TIME message to QGC
Merge pull request #430 from DonLakeFlyer/UnitTestFixes

Unit Tests would not compile, once they compiled, they didn't work correctly, once working correctly they found a couple bugs
Merge pull request #423 from DonLakeFlyer/LinkInterfaceCleanup

Removed LinkInterface methods which were never being called. Updated var...
Merge branch 'master' into alt_speed_fix
Merge pull request #428 from DrTon/alt_speed_fix

Altitude and speed rewrite
Finished work for incoming data rate calculations for the serial link.
Refactored the code to drastically simplify the stats buffer for the SerialLink code. Also added calculation of outgoing data rate.
Added tooltips for max/lifetime data rates to the DebugConsole. Fixed/improved mutexes in SerialLink. Improved timer usage in SerialLink.
Merge branch 'master' into dataRates

Conflicts:
	src/comm/LinkInterface.h
	src/comm/MAVLinkSimulationLink.cc
	src/comm/MAVLinkSimulationLink.h
	src/comm/OpalLink.cc
	src/comm/OpalLink.h
	src/comm/SerialLink.cc
	src/comm/SerialLink.h
	src/comm/TCPLink.cc
	src/comm/TCPLink.h
	src/comm/UDPLink.cc
	src/comm/UDPLink.h
	src/comm/XbeeLink.cpp
	src/comm/XbeeLink.h
Some last clean ups for this branch.