Workaround binary incompatibility with reflection.

Fixes typelevel/wartremover#123.

All the credit to @retronym.
Merge pull request #128 from dwijnand/fix-for-sbt-0.13.6+

Workaround binary incompatibility with reflection.
Exclude code based on file name and not on class/package name

Closes #120.

Resolves #88.

Reverts and fixes #71.