Eirik Hatlen / gammalib

Renamed the GSkyRegionRect::get_corner() method to GSkyRegionRect::corner() and make local coordinate methods provide. Use GSkyPixel to carry local coordinates in units of radians. Extent the GSkyRegionRect::contains() and GSkyRegionRect::overlaps() method to cover all other possible sky region types.

Adjust GSkyRegionCircle and GSkyRegionMap to the new interface and make sure that their contains() and overlaps() method deal with all other regions.

Adjust the GSkyRegionRect unit test accordingly.

…ect centre and their cartesian representation (previous implementation used difference in RA/DEC)

…ng now use of the new PA.