Changes to parametrisation module
Merge branch 'master' of https://github.com/SoFiA-Admin/SoFiA into HEAD
Merge branch 'master' of https://github.com/SoFiA-Admin/SoFiA into HEAD
Change definition of position angle

Added 90 degrees to position angle to ensure that 0 degrees is pointing north. This is the way astronomers would like to have it.
Minor change.
Removed header information from parametrisation

As parametrisation is meant to be happening in pixel coordinates, the FITS file header is no longer required in the parametrisation module. I removed the header data from all functions, and no more header information is passed on to the parametrisation module. This also resolves the issue that data cubes with excessive headers brought SoFiA to a halt.