add_distance_to

[d-chambers]

Description

This PR adds a add_distance_to patch method for calculating the distance to a point specified by a series. It can then be used to sort the channels of the patch. See #429.

Checklist

I have (if applicable):

• [x] referenced the GitHub issue this PR closes.
• [x] documented the new feature with docstrings or appropriate doc page.
• [x] included a test. See testing guidelines.
• [x] your name has been added to the contributors page (docs/contributors.md).
• [x] added the "ready_for_review" tag once the PR is ready to be reviewed.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.84%. Comparing base (8fa6680) to head (620f844). Report is 2 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #430 +/- ## ======================================= Coverage 99.84% 99.84% ======================================= Files 112 112 Lines 9037 9065 +28 ======================================= + Hits 9023 9051 +28 Misses 14 14 ``` | [Flag](https://app.codecov.io/gh/DASDAE/dascore/pull/430/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DASDAE) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/DASDAE/dascore/pull/430/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DASDAE) | `99.84% <100.00%> (+<0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=DASDAE#carryforward-flags-in-the-pull-request-comment) to find out more.

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[d-chambers]

Thanks @ahmadtourei. I implemented your suggestion. I also got thinking and decided to store the origin location as coordinates (not associated with any dimension) rather than attributes. My thinking here is that we may want to support origin being a dataframe in the future, in which case the distance would be the shortest distance to any point in that dataframe. In such a case we would need to store arrays rather than single floats for each coordinate of the origin so this change helps future proof this method.