Add to_file/from_file methods

[pyrates-neuroscience]

Add to_file/from_file methods

[dafrose]

I would like to extend this proposal and state the goal that every object from frontend to backend have file i/o methods. Where possible, these should include yaml readers/writers, but pickle should be available everywhere. Additionally I would like to introduce a mode attribute to the to_file/from_file methods to state whether the target/source file is in yaml/pickle or whatever other format we might introduce in the future. Dedicated methods for different file formats might still exist, but this way we have a single point of entry for saving and loading progress.

[dafrose]

commits 572f127 and fd9892b fix the current implementation of IR pickling and allow to pickle IR instances. In principle all kinds of IR instances are supported, but only CircuitIR is actively tested.

• Still need to test, whether backend stuff is supported.
• Also need to include yaml i/o into these functions

[dafrose]

It might be useful to implement dependent tests, where test 1 creates a network (with backend) and saves the result to file; and test 2 loads that from file and computes. That might cover some relevant use cases.

[Richert]

I implemented yaml-based i/o methods that allow to save AbstractTemplate instances to a yaml file such that it can be loaded back into Python via AbstractTemplate.from_yaml again. Further I/O methods do not make much sense after the backend restructuring, in my opinion, since intermediate representation always have to be build on the fly during a new simulation/file generation call.