Removed some unused debugging code from QGCXPlaneLink.
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.
add eclipse settings folder to gitignore file
Fix broken Windows build

- NAN not available in windows headers, use cross platform friendly
version
- VS compiler does not allow initializing non-integral types in header
files
- ActiveQt libs are already installed by Win Qt4.8.5, no need to build.
Plus this part of the makefile just loops without nmake.exe installed
which is not part of a standard windows box
Merge pull request #442 from DonLakeFlyer/BrokenWindowsBuild

Fix broken Windows build
Merge pull request #440 from thomasgubler/eclipse_gitignore

add eclipse settings folder to gitignore file
Merge pull request #439 from Susurrus/simpleCheckRates

Add data rate calculations for all LinkInterface-derived classes