The default ImageJ groupId changed a while ago

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
DWIM the groupId for jep when it is missing

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
If an aggregator POM specifies explicit dependencies, install them

The sc.fiji:fiji project defines dependencies even if it does not build
an artifact itself. It is a convenient parent for lazy people who simply
want to drag in all of the Fiji components. Also, when calling the
'install' command, we actually want those dependencies installed into
the Fiji.app/ directory.

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

Yesterday, Fiji changed to a slightly different configuration from
before. It used to have a `meta-fiji-external-plugins` project whose
artifact was to be ignored and whose only purpose was to provide the
"bill of materials", i.e. the configuration defining the current
development version of Fiji. Now it is an aggregator POM with the
artifactId 'fiji' that defines dependencies (in the <dependencies>
section, not the <dependencyManagement> section).

This branch supports the new configuration.

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