Dmitry Malyshev / gammalib

The GModelSpatial::region() method returns a pointer to a sky region that fully encloses the spatial model component.

…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.

It seems better to not introduce the alias method but to use a type constructor instead. This allows writing out the same model type that was read in, enhancing the compatibility with the legacy XML format.

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")

…l seem to be biased in the ellipse size.

…runcate ellipse at 3 sigma (#1561).

…ve radius that is consistent with the Gaussian normalization (#1561).

…semimajor and semiminor axis.

Before the limitation was 5 times that values and this led to convergence problems when fitting the model. Limiting the model to 2.5 times the larger axis seems to avoid the problem. Note that this is certainly not a perfect fix of the problem, but it helps to make the working model for now. Solves at least #1561.

…ion is done on an initial call.

Before, the position angle computation was never executed for a position angle of zero. Discovered this by chance ...