Check bincompat on stuff we should be checking bincompat for

[travisbrown]

Fixes #3109. I've also added bincompat checking (currently against 2.0.0 only) for cats-laws, cats-kernel-laws, cats-testkit, alleycats-core, and alleycats-laws.

One piece of breakage slipped into the 2.13 build in #3099. I've verified that Travis CI fails with just the first two commits.

[kailuowang]

thanks very much! assuming build goes green

[travisbrown]

(As a side note, you can check this with show mimaPreviousArtifacts, and the results now look reasonable to me, on both 2.12 and 2.13.)

[codecov-io]

Codecov Report

Merging #3129 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3129   +/-   ##
=======================================
  Coverage   93.19%   93.19%           
=======================================
  Files         376      376           
  Lines        7323     7323           
  Branches      190      190           
=======================================
  Hits         6825     6825           
  Misses        498      498

Flag	Coverage Δ
#scala_version_212	93.53% <ø> (ø)	⬆️
#scala_version_213	90.84% <ø> (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 1a6d2c3...7b4fb0c. Read the comment docs.