bump-pom-scijava: change property range

As the pom-scijava pom.xml now contains multiple properties ranges, it
is not enough to search and replace within the properties tag.

To catch only the first properties section, we now rely on a properly
indented pom-scijava pom.xml, as we harden the sed range by making the
single tab character part of the pattern to match the appropriate section.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
bump-pom-scijava: set profile properties

When bumping pom properties, also bump the corresponding properties in
any profile sections to the latest SNAPSHOT versions.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Teach maven-helper about snapshots from Sonatype

Some of our projects live on OSS Sonatype now, including their snapshot
versions. The Maven helper script needs to handle that case.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
bump-pom-scijava: bump also imglib2-ij.version by default

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Merge branch 'developer-profiles'

This topic branch teaches bump-pom-scijava to update the developer
profiles, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
maven-helper: look for snapshot versions in Sonatype first

Some of our projects migrated from the ImageJ Maven repositories to OSS
Sonatype. These will have obsolete snapshot versions still living in
the ImageJ Maven repository, so let's check with our Sonatype mirror
first, before looking at the ImageJ Maven repository.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>