Modify version.xml to support vRELEASE tags

This commit should add support for tags prefixed with v (as opposed to
v. previously)
Fix omero.v.regexp to preserve compatibility with v.RELEASE tags
Merge pull request #2929 from sbesson/version_prefix

Modify version.xml to support vRELEASE tags
Update develop submodules

Repository: openmicroscopy/openmicroscopy
Already up-to-date.

Repository: openmicroscopy/bioformats
Updating 03d9c5c..87fbabc
Previously merged:
  # PR 1261 rleigh-dundee 'jj2000: Fix compile on Java 8'
  # PR 1270 sbesson 'Use latest/bio-formats5.1 redirects'
  # PR 1136 melissalinkert 'Add initial support for reading BinaryOnly OME-TIFF datasets (rebased onto develop)'

Repository: ome/scripts
Already up-to-date.

Repository: openmicroscopy/ome-documentation
Updating c8357b1..3d2a5a2
Previously merged:
  # PR 944 sbesson 'Use new latest/product5.1 redirects across the board'
  # PR 943 hflynn 'Make Ice 3.5.1 default version'
  # PR 938 rleigh-dundee 'omero: Cpp: Document FindIce changes'
  # PR 940 hflynn 'Tidying a couple of sysadmin docs issues from my absence'

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