Domenico Tiziani / 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")

…tial model component.

The eval() and eval_gradients() methods are expected to return an intensity in units of sr^-1, hence the model value needs to be divided by 4pi.

The formula for drawing random numbers on a sphere was not correct. This has now been corrected, and verify using a dedicated test script (test_model_spatial_const.py).

The coding and design conventions (CDC) document was also updated.

Add GChatter argument to print() method.

The print() method now takes an argument of type GChatter to control the chattiness of the output in a homogenous manner.
Pass NORMAL chatter level in __str__ method.
Add chatter argument to print() methods.
Use GLog::chatter() method to control the chattiness of the log stream operator.
Add chatter() methods and provide member access through const references.
Add chatter() methods, provide member access through const references, and declare one liners as inline methods.

The chatter() methods control the new m_chatter attribute that is used to control the chattiness of the object's print() methods.
name() and version() methods return const references.
logFileOpen() method now sets the chattiness from the applications's chatter parameter, and name() and version() methods now return a const reference.

The eval() and eval_gradients() methods now take a GPhoton object as argument to allow the implementation of energy and time dependent source morphologies.

GEnergy and GTime objects have been added to the mc() method interface to support equally the implementation of energy and time dependent source morphologies.

So far, no class really implements energy and time dependent source morphologies, but now we have the infrastructure to do so.

The GModelPar interface has been revisited and the code has been adapted to satisfy the new interface.

All diffuse spatial models are now derived from GModelSpatialDiffuse and named GModelSpatialDiffuseXXX.