Task #3951 - Clear filename stored in synwinxt on mouse up

- renamed some functions for file drag/drop to be more similar to existing
- improved log messages for the library loader
- removed hack that blocked .exe and .lnk files (annoying for developers)
- removed hack that always clears dragging filename (not very robust)

src/lib/platform/OSXScreen.cpp

@@ -904,7 +904,7 @@ COSXScreen::leave()
 {
     hideCursor();
     
-	if (getDraggingStarted()) {
+	if (isDraggingStarted()) {
 		CString& fileList = getDraggingFilename();
 		size_t size = fileList.size();