Add names to omp critical statements

[JanNiklasB]

Dear All,

with this pull request I want to add names to various #pragma omp critical statements. If such a statement has no name, it blocks every other critical statement with no name, which may cause an increase in runtime. For example, a shell output should only block other shell outputs and not file outputs. Furthermore, if not accessed through a python script but directly through c++, critical statements from the users files may also block critical statements in CRPropa.