Global numerics config

Provides a `GlobalSetupType` containing the types of the global matrix/vector and corresponding linear solver, and use this type in building of processes.
The `ProjectData` now postpones the construction of each process until `ProjectData::processBuilder()` is called (from the main).

For now only LIS and our DenseMatrix types are recoginzed; the petsc configuration is missing. I also would like to move this configuration from compile-time to cmake-configuration-time later on.

If you have suggestions for where to put the `NumericsConfig.h` file and also a namespace, I'll implement it.
Its the same type as boost::ptree.
Boost's ptree is too abstract here, and ConfigTree clarifies that its a kind of config in a tree structure.