Fix in CMake build and support of absolute path for output files

It turned out there was an error in CMake file. It looked for modules in a wrong directory. Also the target name was oni2mov instead of oni2avi.

I also added support of absolute paths for output files. So if user runs oni2avi c:\some_dir\data.oni c:\otherdir\video.avi, then the result files will be in c:\otherdir.