Refactor tuning parameters and fit parameters
To simplify refactoring of SampleModel, the handling of tuning parameters and fit parameters was refactored.
- free tuning parameter tree from SessionModel
- reduce SessionItem exposure at class interfaces
- reduce SessionModel usage
- reduce SessionPath (SessionModel hierarchy) usage
- show units in the tuning tree
- simplify code, remove obsolete code
- minor corrections/refactorings