[WIP] renaming and reordering SDC/MLSDC integrators
states: moved states into utilities
reworked StepSolutionData and TrajectorySolutionData (+tests)
made Spacial Objects comparable and copyable (+tests)
states: reworked NodeState and SequenceState (+tests)
states: reworked MutableStateSequence (+tests)
states: reworked TimeStepState (+tests)
solutions: some further ABC-fication of solutions
states: reworked IterationState and added LevelState (+tests)
states: reworked SolverState (+test)
states: SdcSolverState (+tests)
states: some cleanup and finishing touches
sstates: MlSdcSolverStates (yet untested)
tests: some cleanup
a few adjustments to changed states (not tested or reasoned)
Merge branch 'feature/rewamp-integrators' into feature/rewamping-solver-states

Conflicts:
	pypint/integrators/abstract_integrator.py
	pypint/integrators/mlsdc/explicit_mlsdc.py
	pypint/integrators/mlsdc/implicit_mlsdc.py
	pypint/integrators/mlsdc/mlsdc_integrator.py
	pypint/integrators/mlsdc/semi_implicit_mlsdc.py
	pypint/integrators/sdc/explicit_sdc.py
	pypint/integrators/sdc/implicit_sdc.py
	pypint/integrators/sdc/semi_implicit_sdc.py
	pypint/solvers/i_iterative_time_solver.py
integrators: first tests