Francois Brun / gammalib

…ients argument (#1847)

The eval_gradients() methods duplicate much of the code of the eval() methods. To increase the maintainability of the code, the eval_gradients() methods have been removed, and the computation of partial derivatives is now done by the eval() methods if the optional gradients argument is set to true.

The GModelSpectralRegistry::alloc() method now also checks for the existence of model parameters and allocates the appropriate model from the registry that is found in the XML file base on model type and parameter names. This allows now to have the same model type but different parameter names in the registry.

The spectral model classes have been adapted to the new logic, and models have been added to the registry for all parameter combinations that may exist.

The unit tests and documentation have been updated.

Remove the m_names members from the spatial, spectral and temporal registry classes and directly use the model type to find the appropriate model. The alloc() method now throws an exception if the model is not found. The new logic helped to reduced the code in the client classes (#1824)

Implement the same memory management scheme that was also implemented for the COMPTEL event bin. This enables using an event bin outside an event cube.

Added extensive unit test for the event bin, including the setting of all attributes.

This is in anticipate of the model name changes in release 1.2

This is an anticipation of the renaming of the spectral models that will come in release 1.2.

The following new names have been introduced for the spatial model components:
* "PointSource" (alias: "SkyDirFunction")
* "RadialDisk" (alias: "DiskFunction")
* "RadialGaussian" (alias: "GaussFunction")
* "RadialShell" (alias: "ShellFunction")
* "EllipticalDisk"
* "EllipticalGaussian" (alias: "EllipticalGauss")
* "DiffuseIsotropic" (alias: "ConstantValue")
* "DiffuseMap" (alias: "SpatialMap")
* "DiffuseMapCube" (alias: "MapCubeFunction")

There have been several bugs in the energy dispersion computation in GCTACubeEdisp that prevented a correct computation of energy dispersion. This should now be fixed.