start a new main frame that contains settings editors as tabs
added buttons and current configuration selection (only UI)

* extracted getName() from settings with a name to a new interface
avoid System.exit() at the cost of using reflection
exit through the same way if window manager disposes frame window
implemented select settings for current configuration
activate "Exit" button
make Java3D termination more reliable
added more actions and use them for both menu and buttons

* load RFO
* load STL/CSG
bugfix: do not create an invisible frame as dialog owner
added a status bar to display last loaded file
[draft] started work on new MaterialChooserDialog
redesigned material chooser dialog

got rid of static fields, made a new layout
refactored MaterialChooserDialog and RepRapPlater
added Safe RFO action
added slice action
added slice action to menu
integrate slicing plotter into tabbed pane
show help in tool tip of tabs and ...

* show if slicing is paused in status bar
* register key listener on window level (seems to work more reliable).
added plater actions to main menu

and removed old gui classes
also removed saveSCAD() and reorder() methods from plater
set enabled state for plater actions and ...

removed some "reorder" remains.