Bugfix

geo.raster.conversion:
- raster2polygon: bugfix for not properly handling bad exit status of gdal.Polygonize()

processing.progress_mon:
- Timer:
    - implemented keyword use_as_callback (now properly raises KeyBoardInterrupt in case of TimeOut
    - improved formatting of elapsed time
- ProgressBar:
    - implemented keyword use_as_callback

- updated __version__