Remove panel

[rstoneback]

Description

Addresses #4, start on #3

Removes pandas.Panel from package.

Starts to switch code over to using xarray as main data format rather than something pandas based.

Tweaked general averaging code to reduce specificity with pandas. Started modifying computational_form to enable it's use in more areas.

The code is old, standards wise. Happy to sort that out as time goes on but a decent chunk of existing code may get deleted. I'd rather not make soon to be deleted code pretty. Overall plan is to reserve general comment and docstring improvements until after the transition to supporting xarray, as well as general nD binning support, is complete.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Current suite of unit tests

Test Configuration:

• MacOS 11.5
• Python 3.8
• Any details about your local setup that are relevant

Checklist:

• [x] Make sure you are merging into the develop (not main) branch
• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules
• [x] Add a note to CHANGELOG.md, summarizing the changes

[rstoneback]

Current implementation requires converting each DataFrame to a Dataset. Would likely be better if we could just make a Dataset in a single go. I've been having trouble with that though and wanted to get something up. Working solution > no solution.

[rstoneback]

Thanks for the comments @aburrell. Updated.

[jklenzing]

Just realized the changelog should probably show this as 0.2.0.