Added SkyRegion Base class from pierrick and GSkyRegionCircle derived class
adjust GammaLib.hpp to include GSkyRegion header
adjust overlap from < to <= for consistency
added read and write methods for GSkyRegionCircle and added some exceptions
Added GSkyRegions files
Added GSkyRegions files for compilation.
Added/corrected SWIG files for the GSkyRegion objects
Corrected mistakes in GSkyRegions class
big fixes
Code review before integration.