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/mxdiskstreamprovider.cpp

@@ -1,5 +1,17 @@
 #include "mxdiskstreamprovider.h"
 
+#include "mxthread.h"
+
+// OFFSET: LEGO1 0x100d0f30
+MxResult MxDiskStreamProviderThread::Run()
+{
+  if (m_target != NULL)
+    m_target->WaitForWorkToComplete();
+  MxThread::Run();
+  // They should probably have writen "return MxThread::Run()" but they didn't.
+  return SUCCESS;
+}
+
 // OFFSET: LEGO1 0x100d0f70
 MxDiskStreamProvider::MxDiskStreamProvider()
 {
@@ -11,3 +23,22 @@ MxDiskStreamProvider::~MxDiskStreamProvider()
 {
   // TODO
 }
+
+// Matching but with esi / edi swapped
+// OFFSET: LEGO1 0x100d1750
+MxResult MxDiskStreamProvider::WaitForWorkToComplete()
+{
+  while (m_remainingWork != 0)
+  {
+    m_busySemaphore.Wait(INFINITE);
+    if (m_unk1 != 0)
+      PerformWork();
+  }
+  return SUCCESS;
+}
+
+// OFFSET: LEGO1 0x100d1760 STUB
+void MxDiskStreamProvider::PerformWork()
+{
+  // TODO
+}