Also added wrapper for Metis & ParMetis to prevent it from polluting the global name space

- nesting check macros in iteration macros not working

second tutorial added
updated older tutorials
made tutorials also tests

- Bug occurred if a BufferSystem (or communication scheme) was copied
  and the first object went out of scope.
- Internally a pointer was kept which was still pointing to the original
  BufferSystem

Fixes #16