ProcessTaskManager
* use java.util.concurrent for queue
* signal Cancel/Exception/Stop via the queue
* implements AutoCloseable for try-with-resource
* drain as much Elements as possible from the queue

Improves the performance of "Clean all projects"

For example building platform workspace on Windows
AbstractImageBuilder.compile(): 120 sec -> 80 sec

With this change the Compiler is actually waiting for parsing most time
and not for the write to FileSystem anymore.