Make deepcopy copy num_ghost when using PETSc.
Use super to call pyclaw's deepcopy in parallel.
Fix warning about elementwise comparison to 'None'.
Use deepcopy in _allocate registers, instead of manually copying attributes.
Merge pull request #481 from hadjimy/deepcopy_fix

Deepcopy fix
Merge pull request #482 from hadjimy/comparison_to_None_fix

Fix warning about elementwise comparison to 'None'.
Update variable step-size SSPLMM.
Make a function to accept/reject step and update code for new step-size calculatiob.
Update pyclaw solver to match with changes in sharpclaw solver.
Edit how cfl number is updated, so cfl at each step relates with current solution.
Reset local cfl at the beggining of step in classic.
Add functions for accept/reject step and new step-size choice for classic. Remove step_index reset to sharpclaw solver.
Major edits/corrections in accept/reject step and new step-size setup. step_index is updated only when step is accepted.
Correct step-size update at the last RK step.
Improve the way information from previous steps is updated.
Make LMM tests pass.

Also:
- Change LMM names from 'MS' to 'LMM'
- Make step rejection work correctly for LMMs
- Allow use of grid norms in util.check_diff() by passing delta
Update regression data for WC blast test.

Due to step rejection occurring since we now check the CFL
number for all RK stages.
Rebase master.