Minor formatting
Replace exception with a null image
Replace exception with return statement
Initialize all members in init-list
Add constructor for QImage
Add constness
Bugfix: App crashes if avisynth returns an invalid frame and throws

Sometimes the avisynth wrapper might throw from getFrame which propagates
and is not handled anywhere. This fix catches it early and returns an empty QImage instead
Revert C++ style casting back to C style to fix a bug in loading the library

The program would fail to load the avisynth library with the modification
Change application version number