Make sure to override toXxx methods when it’s a no-op

* 1.0.x: (28 commits)
  Split compiler bridge tests to another subproject
  Implement compiler bridge for 2.13.0-M2
  Add yourkit acknoledgement in the README
  "sbt '++ 2.13.0-M2!' compile" does not work with sbt 1.0.0
  Add header to cached hashing spec
  Add headers to missing files
  Fix scala#332: Add sbt-header back to the build
  Update sbt-scalafmt to 1.12
  Make classpath hashing more lightweight
  Fix scala#442: Name hash of value class should include underlying type
  source-dependencies/value-class-underlying: fix test
  Ignore null in generic lambda tparams
  Improve and make scripted parallel
  Fix scala#436: Remove annoying log4j scripted exception
  Fix scala#127: Use `unexpanded` name instead of `name`
  Add pending test case for issue/127
  source-dependencies / patMat-scope workaround
  Fixes undercompilation on inheritance on same source
  Add real reproduction case for sbt/zinc#417
  Add trait-trait-212 for Scala 2.12.3
  ...

 Conflicts:
	internal/zinc-apiinfo/src/main/scala/sbt/internal/inc/ClassToAPI.scala
	project/build.properties
	zinc/src/main/scala/sbt/internal/inc/MixedAnalyzingCompiler.scala

The ClassToAPI conflict is due to:
* sbt/zinc#393 (a 1.x PR), conflicting with
* sbt/zinc#446 (a 1.0.x PR).

The build.properties conflict is due to different PRs bumping
sbt.version from 1.0.0 to 1.0.2 to 1.0.3. (scala#413, scala#418, scala#453).

The MixedAnalyzingCompiler conflict is due to:
* sbt/zinc#427 (a 1.x PR), conflicting with
* sbt/zinc#452 (a 1.0.x PR).

* 1.0.x: (28 commits)
  Split compiler bridge tests to another subproject
  Implement compiler bridge for 2.13.0-M2
  Add yourkit acknoledgement in the README
  "sbt '++ 2.13.0-M2!' compile" does not work with sbt 1.0.0
  Add header to cached hashing spec
  Add headers to missing files
  Fix scala#332: Add sbt-header back to the build
  Update sbt-scalafmt to 1.12
  Make classpath hashing more lightweight
  Fix scala#442: Name hash of value class should include underlying type
  source-dependencies/value-class-underlying: fix test
  Ignore null in generic lambda tparams
  Improve and make scripted parallel
  Fix scala#436: Remove annoying log4j scripted exception
  Fix scala#127: Use `unexpanded` name instead of `name`
  Add pending test case for issue/127
  source-dependencies / patMat-scope workaround
  Fixes undercompilation on inheritance on same source
  Add real reproduction case for sbt/zinc#417
  Add trait-trait-212 for Scala 2.12.3
  ...

 Conflicts:
	internal/zinc-apiinfo/src/main/scala/sbt/internal/inc/ClassToAPI.scala
	project/build.properties
	zinc/src/main/scala/sbt/internal/inc/MixedAnalyzingCompiler.scala

The ClassToAPI conflict is due to:
* sbt/zinc#393 (a 1.x PR), conflicting with
* sbt/zinc#446 (a 1.0.x PR).

The build.properties conflict is due to different PRs bumping
sbt.version from 1.0.0 to 1.0.2 to 1.0.3. (scala#413, scala#418, scala#453).

The MixedAnalyzingCompiler conflict is due to:
* sbt/zinc#427 (a 1.x PR), conflicting with
* sbt/zinc#452 (a 1.0.x PR).

Rewritten from sbt/zinc@e245d95

…er-5.0.8

Bump html-proofer from 4.4.3 to 5.0.8

context is scala#332 -- Fabien says our infra is on 3.2.3 now,
so I think we should match that in CI