Remove deprecated MPI::num_processes and process_number.
Remove deprecated Function::update.
Make deprecation warnings for double init of petsc matrix into errors.
Change v.cell().d to len(v) in book test. This has been deprecated for a long time now.
Remove gitignore rules that hide all test and demo files!!!
Fix in new multistage utility not py3 compatible.
Minor fix in test.
Merge branch 'martinal/fix-py3-multistage-issue'
Merge branch 'martinal/topic-remove-deprecated-code'