POM: update to scijava-common 2.16.0

This version adds the UI subsystem, formerly known as ij-ui.
Add UI subsystem for images

It was migrated from ImageJ:
https://github.com/imagej/imagej/tree/imagej-2.0.0-beta-7.9/core/ui

It depends on the new SciJava Common UI subsystem:
https://github.com/scijava/scijava-common/commit/0d4b014dae36deae4a457a3ab3ed9595c6a3f601
ImageJApp: make high priority

This makes the ImageJ app take precedence
over "normal" apps such as SCIFIO.
AbstractImageDisplayViewer: add "(V)" trailer

When the image is a "virtual" one (i.e., a SCIFIO cell image), we put a
"(V)" in the title bar. This is a holdover from ImageJ1, and it would be
good to do something more sensible in the future, but for now, as a
simple indicator, it is better than nothing.

This logic was formerly (erroneously) in AbstractDisplayViewer.
ImageJApp: remove redundant getTitle() method

The latest SciJava Common release handles it in the AbstractApp layer.
ImageJApp: fix out-of-date artifactId
ConfigFileParameters: get base directory from App

This is more flexible than grabbing it via a static utility method.
AppUtils: deprecated getBaseDirectory() method

It is more flexible to call getBaseDirectory() on the App from the
AppService instead.
Merge branch 'ui-split'

This branch migrates the image-specific portion of ij-ui; see:
https://github.com/imagej/imagej/tree/imagej-2.0.0-beta-7.9/core/ui

The non-image-specific portion migrated to SciJava Common:
https://github.com/scijava/scijava-common/commit/0d4b014dae36deae4a457a3ab3ed9595c6a3f601