Resolve "Add simple adaptive timestepping"

What does this MR do?

• Remove coefficient mapper and its use on local operators
• Remove the operator map of objects within the model class
• Move read/write responsibility to model state
• Allow states to be independent of models. Thus, allowing several different states coexist for a given model.
• Multiple domain model now needs only one file path and each sub-domain file name is deduced from the state.
• Writer might write on different files on request
• Clean up logger output
• Update meaningful logging values on the ini file
• Improved errors when a config file is incorrect
• Default executable now use simple adaptive steppers
• Stepper now can use all PDELab RK methods
• Fix scalar error on the gaussian equation used for comparison

Is there something that needs to be double checked?

For some reason, single domain and multidomain executables report different precision when comparing gaussian solutions. This problem was caused by an error in the dune_copasi_md_compare executable.

Can this MR be accepted?

• Implemented
• Added/Updated tests:
• Added/Updated (C++) documentation
• Pipelines passing
  • 
  • 
  • 
• Delete branch option set
• Added entry to CHANGELOG.md

Related issues

Closes #26 (closed), #28 (closed) , #12 (closed)