Post-upload import step notifications added.

Temporary PROGRESS_EVENTs added to mark the ends of the current 5 import steps
following file upload.
Switch order of import step notifications to reflect steps in ManagedImportRequestI.
Re-organise file upload events.
Fix second conflict
Adding back deleted subclass to fix build.
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 587 (Modulo retrieve (rebased onto develop))
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 599 (scons: Update to version 2.2.0)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 634 (Big images fs 9701 (develop))
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 636 (Render fs speed 10183 develop)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 642 (Add AssumeNG to repository (see #10238))
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 645 (xsd-fu cleanup)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 654 (Rebased onto develop of spec clean PR)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 655 (Merge xsd-fu changes from schema-2012-06)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 659 (Add a script for running all of the necessary xsd-fu commands)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 669 (Introduce FsFile-based representation of checked paths and adjust destination of imported files.)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 670 (Post-upload import step notifications added.)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 672 (Web fs image links)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 678 (Calculate hash digests on a per plane basis (Fixes #10073))
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 679 (Update submodules)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 681 (Download)