Give the default model a name
Update FieldPanel#getField and #setField

FieldPanel now behaves like DroplistPanel and ClosePanel -- the get/set
methods access the widget, not the value of the widget.

Updated dependencies, as well.
Add RadioButtonPanel

It's a GWT composite that displays a label and a pair of radio buttons
wrapped in a HorizontalPanel.
Update internal layout of FieldPanel

Again, to make it more like other Panels.

Also reduce cell spacing in all Panels.
Start configuring SaveDialogBox for projects

Add new widgets to set the visibility, the driver and the case. Use a
Grid to align the widgets.
Set vertical alignment of label in DroplistPanel

It should be middle-aligned.
SaveDialogBox takes DataManager object as parameter

The DataManager is needed to add content to the widgets in the
SaveDialogBox.
Show driver of model being saved in SaveDialogBox

If no driver has been set for the model, display the name of the first
component in the list.
Make a static variable for the default model name

Set it in DataManager.