Merge pull request #841 from mlangc/master

Show @return in scaladoc hovers
Revert "Interrupt Scala builder on resource change"
Create a build marker when a project is not built due to upstream errors.

Fixed #1002320
Merge pull request #845 from scala-ide/revert-767-t1002229-interrupt-build

Revert "Interrupt Scala builder on resource change"
Merge pull request #846 from dragos/issue/no-build-markers-downstream

Create a build marker when a project is not built due to upstream errors...