h1. GammaLib 00-06-00 release

The release includes the following changes:

* Add support for Fermi/LAT Pass 7 data
* Add GModelSpatialMap model
* Add sky direction access operator to GSkymap class
* Add support for diffuse source models to CTA response
* Add OpenMP support and parallelize likelihood optimizer
* Add unit test support (introduce test module)
* Correct bugs in GSparseMatrix
* Enhance code quality