update slider for work with java9
Compile examples in the Travis build.

The subproject containing the examples (added in 8db44f35a0)
is not aggregated under the root project, and as such is not
part of `sbt compile`.

This commit adds the task `examples/compile` to the SBT command
line in the Travis CI build.
Merge pull request #17 from andy1138/java9

update slider for work with java9
Merge remote-tracking branch 'scala-swing/java7' into java7
SimpleSwingApplication extended by companion objects.
Merge branch 'review/18/travis-examples' of https://github.com/retronym/scala-swing into swingtut

Merge of a large number of tutorial examples.
Make lazy val references to the MainFrame variable in most of the tutorials.
Remove the spurious comment that the process method is never called by the SwingWorker in IconDemoApp.scala.  It is getting called now.
Remove unneeded references to the peer's minimumSize, preferredSize, and size.
Get rid of deprecated procedure syntax instances.
Factor out common code that is getting icons from the same directory.
Fix the caret event handling.  Fix undo and redo menu items using javax swing custom actions attatched to menu item peers.
Rewrite of the undo and redo actions so that no use is made of the menu item peers or action peers.  Use Swing.onEDT to place this computation on the Swing event dispatch thread.  Fix the caret event handling.
Move TextPane from the end of TextSampleDemo into /scala/swing as a Swing component in its own right.  Change the source code and html for the TextSampleDemo so that it refers to scala.swing components instead of swing jcomponents.
Fixed a comment in Utils that said a null is returned when instead an Option.None is returned.
Remove scala.swing.examples.tutorials.components.Utils.  It is used by FileChooserDemo2 which is not scalified yet.
Adding the example source directory as a source path in Eclipse added more dot files that we do not want in git.
Move the ToolBar out of the tutorial code and into scala/swing.  Change ActionDemo so that scala-swing events are used instead of an ActionListener.
Simplify exception handling in FocusConceptsDemo by using NonFatal.
Replace bad var declarations with good val declarations.