GUI redesign

[HEdingfield]

• Get rid of the startup menu screen in favor of going straight to the config creator
• Move buttons to top above tabs; add buttons for new, load, tabulate, and quit
• Save button should read "Save..." to indicate that it'll summon a dialog
• A label at the top should communicate what's currently loaded (else say something like )
• Save listener (see Create save listener for GUI #134) checks need to occur on new, load, tabulate, quit and alert user asking if they want to save first
• Add and Delete buttons need to be placed so that they are more intuitive (for CVR sources and possibly candidates)
• Delete Selected buttons should be disabled if nothing is selected
• Ability to drag and edit rows (e.g. for candidate permutations)

[gngilbert]

Can't tell how much of this has been addressed.

[HEdingfield]

This has mostly all been addressed and is superseded by #461 anyway. Moving any last unresolved items to that issue.