Tidied up build.

Disabled aggregation of "doc" task in "root" project, removing previous
fudge (giving "doc" no files to work with in the "macros" and "core"
projects). Also removed another hack (empty artifact repository) that
was no longer required.
Removed redundant Maven & style files.
Used simpler timestamp method for timestamping build.
Replaced org.joda.time classes with new Java 8 java.time classes.

Relocated org.facsim.util package object from "Macros" sub-project to
"Core" sub-project. Also added project start date to build.
Added class to implement Behavior trait using Manifest data.
Fixed some SBT Eclipse plugin settings.

The root project was no longer being generated. Also specified that this
project has no source directories (so none are generated in Eclipse).
Bumped SBT Eclipse plugin to latest version.
Merge remote-tracking branch 'origin/master'
Removed deprecated (as of Scala 2.11) -Ynotnull compiler option.
Bumped Scalatest to latest version (v2.2.0).
Removed redundant FindBugs preferences file.
Bumped Scalastyle up to the latest revision.
Bumped ScalaFX up to latest snapshot.
Added check for Java 8 or higher runtime during build.
Fixed a typo.
Refactored application classes.

Improved JAR file manifest handling and testing. Added test JAR files.
Simplified application classes.
Improved application definition.

App now initializes as a JavaFX application, with title and icons defined
automatically.
Updated & corrected documentation.
Added autoShow application property.

This property determines whether the application's primary stage is
shown automatically during construction.
Switched from sbt-git plugin to sbt-release.

 This switch was made to simplify the automated release process.