-Multithreaded uploading with configurable number of threads.
-Adds support for an explicit matching filter that will only build an assessor if the specified artefacts match across the inputs. This allows us to ensure that an assessor will only use the set of assessors that are built on the same scan.
-Adds support for uploading by reference. This allows us to mount the DAX Upload Directory on the XNAT server and then use the XNAT API to supply a reference to the directory we want to upload. Therefore, rather than uploading files directly through the API, we bypass http and the files are directly copied over the native filesystem.
-Bugfixes for XnatSwitch
-Bugfixes for Xnatdownload