Reorganize extlinks and allow to pass SOURCE_USER for Github links

Reorganize extlinks to mirror organization of conf.py of ome-documentation.git
Fix Bio-Formats Jenkins job alias
Add Sphinx documentation for Inveon
Do not recommend using "Plugins > LOCI > Update LOCI Plugins" in Fiji
Update screenshot of file grouping window
merge develop --exclude conflict needs-fixes broken: PR 317 (Add support for Inveon data)
merge develop --exclude conflict needs-fixes broken: PR 318 (PR 201 on develop)
merge develop --exclude conflict needs-fixes broken: PR 319 (Add support for JPEG-2000 compression with code 34712)
merge develop --exclude conflict needs-fixes broken: PR 320 (ImageJ plugin option improvements)
merge develop --exclude conflict needs-fixes broken: PR 321 (Sprint3 bug fixes develop)
merge develop --exclude conflict needs-fixes broken: PR 323 (Extlinks review (rebased onto develop))
merge develop --exclude conflict needs-fixes broken

Repository: openmicroscopy/bioformats
Updating 96c615b..25bef48
Merged PRs:
  # PR 317 melissalinkert 'Add support for Inveon data'
  # PR 318 melissalinkert 'PR 201 on develop'
  # PR 319 melissalinkert 'Add support for JPEG-2000 compression with code 34712'
  # PR 320 melissalinkert 'ImageJ plugin option improvements'
  # PR 321 melissalinkert 'Sprint3 bug fixes develop'
  # PR 323 sbesson 'Extlinks review (rebased onto develop)'

Generated by OMERO-merge-develop#92 (http://hudson.openmicroscopy.org.uk/job/OMERO-merge-develop/92/)