Tensor pomeron cmake

The tensor pomeron paper (arXiv:1901.08524) is accepted by the PRD: publishing fitting module corresponding to it.

Apart from the new theory module ("TensorPomeron") and corresponding test, there are small changes related to the treatment of the default evolution. For non-DGLAP reactions it is not required, thus it is not loaded by default and instead only loaded when requested. As a side effect, this allows for simplified parameters.yaml file (without evolution). See defaultEvolutionInstance() function instead of defaultEvolution global variable.