Improved docstrings in lib/_augment.pyx

[zemanj]

Fixes (partially) #2046, this is the second of a series of related PRs, following PR #2048.

Changes made in this Pull Request:

• Improved documentation of MDAnalysis.lib.distances.augment_coordinates() and MDAnalysis.lib.distances.undo_augment() to better explain what the methods are actually doing.
• Added corresponding .. autofunction in lib/distances.py so that the signatures of both functions are now properly displayed in the html docs.
• Corrected a mistake from PR Simplified code in lib.distances a bit #2048 so that distance_array() now also returns an array for single coordinate input.
• Added missing CHANGELOG entries for PR Simplified code in lib.distances a bit #2048.

Apparently, there is a problem with Windows/Linux (i.e., CRLF vs. LF) line endings resulting in an incorrect git diff output for lib/_augment.pyx, which now looks as if I changed every line in the file, even though I only changed the docstrings. With git diff -b the changes are displayed correctly, though. On github, just change the diff settings to ignore whitespace.

PR Checklist

• Tests?
• Docs?
• CHANGELOG updated?
• Issue raised/referenced?

[zemanj]

@ayushsuhane Since you wrote the augment routines (PR #1977), could you take a quick look at the new docstrings? Just to make sure I didn't add any bogus. 😉

[codecov]

Codecov Report

Merging #2062 into develop will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #2062   +/-   ##
========================================
  Coverage    89.26%   89.26%           
========================================
  Files          159      159           
  Lines        18678    18678           
  Branches      2673     2673           
========================================
  Hits         16672    16672           
  Misses        1403     1403           
  Partials       603      603

Impacted Files	Coverage Δ
package/MDAnalysis/lib/distances.py	95.34% <ø> (ø)	⬆️

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[zemanj]

Mmmh... nobody up to reading some good ol' poetry? 😄

[ayushsuhane]

@zemanj Looks good. The docs are more clear now. Thanks!! 👍

[richardjgowers]

thanks for the review @ayushsuhane

[zemanj]

The develop build is now failing for Python 3.4 due to an unresolvable conda dependency. I restarted the build but the problem persists.