Start 2.1.0-dev0

[IAlibay]

Fixes #3254

Changes made in this Pull Request:

• Starts off 2.1.0-dev0
• Raises minimum python version to 3.7 and numpy to 1.18 in accordance to current NEP29 support. If we have an idea of when the release is going to be we can provide a more accurate minimum version here. Ideally I'd like 2.1.0 to be out faster than normal so we can add the RDKit fixes.

PR Checklist

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

[IAlibay]

Important! Please do not squash-merge! This includes the master commits that will bring the two branches back to parity.

[IAlibay]

Not really thought about what we'll do if we want to do a bugfix for 2.0.0, I guess we can just do a feature branch from master?

[codecov]

Codecov Report

Merging #3400 (993ee16) into develop (b43f0bb) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop    #3400      +/-   ##
===========================================
- Coverage    93.79%   93.79%   -0.01%     
===========================================
  Files          177      177              
  Lines        23233    23228       -5     
  Branches      3309     3308       -1     
===========================================
- Hits         21792    21787       -5     
  Misses        1390     1390              
  Partials        51       51              

Impacted Files	Coverage Δ
package/MDAnalysis/core/universe.py	97.95% <100.00%> (-0.03%)	⬇️
package/MDAnalysis/version.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b43f0bb...993ee16. Read the comment docs.

[IAlibay]

@MDAnalysis/coredevs we need to get this moving along so that we can get dev back up.

[IAlibay]

The conversation to be had here is if we want to wait to apply NEP29 until after we know we don't want a bugfix for 2.0.0? If so I can revert some of the changes here and keep 3.6 support until we drop it later?

[orbeckst]

Let’s do this in forward looking mode. (The alternative would have been to set the version to 2.0.1 and change it as soon as a new feature goes in.)

Let’s try to make PRs focused so that we could easily backport them to a patch branch on master. Or if we only have fixed on this branch when merging into master we can just change the version information there and then change develop.

[IAlibay]

Let’s do this in forward looking mode. (The alternative would have been to set the version to 2.0.1 and change it as soon as a new feature goes in.)

Sounds good to me. If anything I'd like to get 2.1.0 out faster (especially so we could get #3044 out there).