Add support for behaviour post-processings

[thelfer]

The available postprocessings are described by the postprocessings member of the Behaviour class which associates the name of the postprocessing and a small data structure containing:

• the pointer to the postprocessing,
• the list of outputs of the postprocessing.

The getPostProcessingVariablesArraySize function returns the size of an array able to contain the outputs an postprocessing for an integration point.

The allocatePostProcessingVariables functions return an array able to store the outputs of a postprocessing for a given integration point or a set of integrations points.

The executePostProcessing functions execute a postprocessing on a unique integration point or a set of integration points.

Example of usage

auto m = MaterialDataManager{b, 2u};
// initialize the state and perform the behaviour integration
...
// execute the post-processing
auto outputs = allocatePostProcessingVariables(m, "PrincipalStrain");
executePostProcessing(outputs, m, "PrincipalStrain");