Feature to drag a file from Windows to Mac:

- On Mac client main thread is used for cocoa application in order to simulate drag.
- Send dragging file dir from Windows server to Mac client while dragging after switching screen.
- Dragging information sending is immature now (need to support multi files dragging in the future).
- Used Cocoa function to monitor dragg pasteboard.
- Changed Mac client to use another thread for event queue instead of the main thread.
- Change fileRecieveComplete to fileRecieveCompleted.

src/lib/synergy/CScreen.cpp

@@ -415,12 +415,36 @@ CScreen::pollActiveModifiers() const
 	return m_screen->pollActiveModifiers();
 }
 
+bool
+CScreen::getDraggingStarted() const
+{
+	return m_screen->getDraggingStarted();
+}
+
+void
+CScreen::setDraggingStarted(bool started)
+{
+	m_screen->setDraggingStarted(started);
+}
+
+void
+CScreen::startDraggingFiles(CString str)
+{
+	m_screen->fakeDraggingFiles(str);
+}
+
 CString&
 CScreen::getDraggingFileDir() const
 {
 	return m_screen->getDraggingFileDir();
 }
 
+const CString&
+CScreen::getDropTarget() const
+{
+	return m_screen->getDropTarget();
+}
+
 void*
 CScreen::getEventTarget() const
 {