Remove obsolete SwingUtils class
POM: rename base POM to pom-ij-base

This avoids a name clash with pom-imagej, which we will now use for an
external common parent POM for all Maven projects in the ImageJ org.
POM: bump to pom-scijava 1.163
POM: remove distributionManagement section

The way to deploy to the ImageJ Maven repository is now by passing
"-Pdeploy-to-imagej" which is inherited from the pom-scijava parent.
POM: remove obsolete comment

The ImageJ repository is no longer included for the pom-scijava parent,
since pom-scijava is now available from Maven Central.
ImageJ: remove redundant input() method

It is part of the AbstractGateway now.
Organize imports
Make AWT and Swing projects external

See:
* https://github.com/imagej/imagej-ui-awt
* https://github.com/imagej/imagej-ui-swing
* https://github.com/scijava/scijava-ui-awt
* https://github.com/scijava/scijava-ui-swing
Make Updater project external

See:
https://github.com/imagej/imagej-updater
Migrate core options to imagej-common component

See:
https://github.com/imagej/imagej-common/commit/16f7d05729a8269c33c2383691933454296bf37d
Migrate TunePlayer to SciJava Common

See:
https://github.com/scijava/scijava-common/commit/2a40b7718d998b873cd2c08837c3271cac9d4091
Migrate core commands to external repositories

See:
* https://github.com/imagej/imagej-plugins-commands
* https://github.com/scijava/scijava-plugins-commands
POM: switch to pom-imagej parent

This eliminates a lot of redundant boilerplate!
Merge branch 'awt-split'

This branch externalizes many components:
* All remaining UI components (AWT and Swing)
* The Updater
* Core options
* Core commands

------------------------------------------------------------------------
The specific project migration paths are:

core:
ij-options                -> https://github.com/imagej/imagej-common
ij-updater-core           -> https://github.com/imagej/imagej-updater

plugins/commands:
ij-commands               -> https://github.com/imagej/imagej-plugins-commands
                             https://github.com/scijava/scijava-plugins-commands

plugins/uis:
ij-ui-swing               -> https://github.com/imagej/imagej-ui-swing
                             https://github.com/scijava/scijava-ui-swing
ij-ui-awt                 -> https://github.com/imagej/imagej-ui-awt
                             https://github.com/scijava/scijava-ui-awt

ui/awt-swing:
ij-ui-common-awt          -> https://github.com/scijava/scijava-ui-awt
ij-util-awt               -> https://github.com/scijava/scijava-ui-awt

ui/swing:
ij-ui-swing-commands      -> https://github.com/imagej/imagej-ui-swing
                             https://github.com/scijava/scijava-ui-swing
ij-ui-swing-script-editor -> https://github.com/imagej/imagej-ui-swing
ij-ui-swing-tools         -> https://github.com/imagej/imagej-ui-swing
ij-ui-swing-updater       -> https://github.com/imagej/imagej-ui-swing
ij-util-swing             -> https://github.com/scijava/scijava-ui-swing

------------------------------------------------------------------------
From the perspective of the new repositories:

ImageJ Common - https://github.com/imagej/imagej-common
* ij-options

ImageJ Plugins: Commands - https://github.com/imagej/imagej-plugins-commands
* ij-commands (image-specific ones -- most of them)

ImageJ UI: AWT - https://github.com/imagej/imagej-ui-awt
* ij-ui-awt (image-specific classes)

ImageJ UI: Swing - https://github.com/imagej/imagej-ui-swing
* ij-ui-swing (image-specific classes -- e.g., overlays w/ JHotDraw)
* ij-ui-swing-commands (image-specific -- e.g., Overlay Manager)
* ij-ui-swing-script-editor
* ij-ui-swing-tools
* ij-ui-swing-updater

ImageJ Updater - https://github.com/imagej/imagej-updater
* ij-updater-core

SciJava Plugins: Commands - https://github.com/scijava/scijava-plugins-commands
* ij-commands (imagej-agnostic -- only a few)

SciJava UI: AWT - https://github.com/scijava/scijava-ui-awt
* ij-ui-awt (imagej-agnostic classes -- menus & widgets)
* ij-ui-common-awt
* ij-util-awt

SciJava UI: Swing - https://github.com/scijava/scijava-ui-swing
* ij-ui-swing (image-agnostic classes -- menus, widgets, etc.)
* ij-ui-swing-commands (image-agnostic -- e.g., Command Finder)
* ij-util-swing