MxSemphore + MxThread + MxThread implementions (#80)

* Add MxSemphore + MxThread and the two implementations I could find
  of MxThread (consumers extend it and override the Run method).

* Implement a function in MxDiskStreamProvider which uses thread and
  semaphore to confirm correct layout / size of those classes.

* All 100% match except two functions with a pair of registers swapped.

LEGO1/mxtimer.h

@@ -18,7 +18,7 @@ public:
   inline MxLong GetTime()
   {
     if (this->m_isRunning)
-      return s_LastTimeCalculated;
+      return s_LastTimeTimerStarted;
     else
       return s_LastTimeCalculated - this->m_startTime;
   }