Move libmdanalysis to lib

[hmacdope]

Fixes #3912

Changes made in this Pull Request:

• Moves the libmdanalysis init.pxd file to lib.

PR Checklist

• CHANGELOG updated?
• Issue raised/referenced?

[codecov]

Codecov Report

Base: 94.35% // Head: 94.35% // No change to project coverage 👍

Coverage data is based on head (e9d9b65) compared to base (345d5d2).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #3913   +/-   ##
========================================
  Coverage    94.35%   94.35%           
========================================
  Files          194      194           
  Lines        25060    25060           
  Branches      3392     3392           
========================================
  Hits         23645    23645           
  Misses        1366     1366           
  Partials        49       49           

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[IAlibay]

Since this made it to 2.3.0, do we think the userbase was large enough that we need to semver or are we happy going ahead with the change?

Also were there any docs associated with this?

[hmacdope]

I don't think there is a need to semver, but there should be docs in the developer docs. Ill add them.

[IAlibay]

I'm just going to put this down as a "approved", but we should get those docs in somewhere.

[orbeckst]

lgtm

[hmacdope]

Cheers, new issue raised #3921