Added class for periodic realtime threads. Not tested yet
Periodic thread seems to work
Mutexes are now working

The output of the example program will sometimes be mixed between
thread1 and thread2 because the cout object is not protected by a mutex
or similar.
Changed file name for threading example, so it is no cpp-file anymore
Added very basic support for minimu9 !not yet tested in any way!
Some changes to make solve compiler warnings