#985 "Upload: better way to interrupt upload from server"

- Multipart: mark state as Interrupted when possible
- client: call Upload.progress even if missing progress-received and progress-expected
- combineValues: support any value
- oxf:xforms-upload processor
- Iterator.headOption
- Boolean.iterator
- Try.cleanup/rootFailure/iterator
- oxf:request: some refactoring for reuse
- HttpStatusCodeException: Throwable for information