IPS API Improvements

[PythonFZ]

Please leave any comment or idea on how to improve the IPS API here.
If you are certain about your idea feal free to make an issue instead.

[PythonFZ]

Have an option, that only saves parameters and changes in new nodes that haven't been on the graph before.
Have an easy way to select the nodes you want to save. Maybe project.save(...) instead of project.run()?

with ips.Project(only_save_new_nodes: bool)