Update to rail v2.0: Parameter changes, ephemeral DataStore and interactive package

[jscora]

Problem & Solution Description (including issue #)

This PR involves the following changes:

• adds an interactive subpackage that allows notebook users to use one function instead of the make_stage/run stage steps
• changes the DataStore to be instatiated on a per-stage level, so each stage only has access to its own DataStore
• adds some new Shared Parameters and updates to parameter names as discussed in issues Allow different default values to be set for Shared Parameters and add new Shared Parameters #233 and Rename parameters and replace with Shared Parameters #234
• some documentation updates

Code Quality

• My code follows the code style of this project
• I have written unit tests or justified all instances of #pragma: no cover; in the case of a bugfix, a new test that breaks as a result of the bug has been added
• My code contains relevant comments and necessary documentation for future maintainers; the change is reflected in applicable demos/tutorials (with output cleared!) and added/updated docstrings use the NumPy docstring format
• Any breaking changes, described above, are accompanied by backwards compatibility and deprecation warnings

[eacharles]

I'm wondering a bit about the process you envisage for keeping the .pyi files up to data.

Thanks for all the very nice work.

[jscora]

I'm wondering a bit about the process you envisage for keeping the .pyi files up to data.

Thanks for all the very nice work.

That's a good question -- we can go over it a bit in the meeting on Monday, but our current thought is to add a test to the smoke tests that checks if the .pyi files need to be updated, and then will output the appropriate error message so it will be obvious that what needs to happen is a quick PR where you just run the script to create the .pyi files again.