POM: bump to pom-scijava 1.161

This updates the version of ImgLib2 to 2.0.0-beta-26, and adjusts
accordingly for breaking API changes.

It also updates scijava-common to 2.15.0, which includes many new
services migrated from ImageJ core.
Migrate to SJC version of core services & plugins

See:
https://github.com/scijava/scijava-common/commit/3aa51f812fef19cd14e3adea4d4aa5e3b395f1ea
POM: add dependency comments
Organize imports
Remove Swing-specific widget

The code has migrated to ImageJ:
https://github.com/imagej/imagej/commit/d0e7a1eee1683e523309588c6bbb31e99743b212
Migrate to ImageJ Common component

See:
https://github.com/imagej/imagej-common
Rename package prefix to net.imagej

This is more standard with the rest of the SciJava software stack.
Merge branch 'mega-split'

This branch update ImageJ OPS to use the new split ImageJ Common
library. It also updates the package prefix to net.imagej.ops for
consistency with the rest of SciJava.

See:
https://github.com/imagej/imagej-common