What does this implement/fix? Explain your changes.

• Add coverage (cs code limited to windows, no mature coverage tools for mono)
• Speed up AppVeyor by 50%, conda recipes built only when pull_request
• Speeds up Travis ~30% by using containers
• Simplifies and unfreezes mono setup

Does this close any currently open issues?

#237
#334

Any other comments?

Redid the previous pull request. (#335)

Sample coverage report.

Codecov Report

❗ No coverage uploaded for pull request base (master@ef133a3).

@@           Coverage Diff            @@
##             master    #345   +/-   ##
========================================
  Coverage          ?   61.1%           
========================================
  Files             ?      61           
  Lines             ?    5324           
  Branches          ?     897           
========================================
  Hits              ?    3253           
  Misses            ?    1832           
  Partials          ?     239

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 ef133a3...1145a44. Read the comment docs.