Meta-issue for changes to other projects

Here are some things we should consider for the next feature push after 1.0, even though they would involve changes to projects other than Truth:

- [Multline-friendly `toString()` for AutoValue](https://github.com/google/auto/issues/730)
- More Error Prone checks for Truth usages [edit: internal bug 134041650]
- In particular, see internal bug "EqualsIncompatibleType for Truth." (A version already exists but could be improved.)
- Changing Error Prone's testing library (the one that's based on [`BUG: Diagnostic contains`](https://github.com/google/error-prone/blob/5871842defabd64dcce0ddba35b0e05c7bd939bc/core/src/test/java/com/google/errorprone/bugpatterns/testdata/ChainingConstructorIgnoresParameterPositiveCases.java#L40)) to use Fuzzy Truth
- Changing Compile-Testing (I think? whatever some of our Refaster tests use internally) to provide its expected and actual values to Truth in a format that we can turn into a `ComparisonFailure` [edit: internal bug 25861945, also https://github.com/google/compile-testing/issues/16]