Giant batch of updates

Off the top of my head:

 *Import/Export of scripts:
    Allows script archives to be converted to
    and from a plain text representation, which
    can be used with eg. version control.

 *No accidental loss of changes:
    Window title indicates whether modifications
    have been made (with a '*'), and whenever an
    action occurs that might change the current
    script set (Open, Close, Import, Quit), a
    confirmation dialog will offer to save the
    changes before proceeding with the action

 *Dedicated editor instances for each script:
    Changing the active (visible) script using the
    left bar will no longer reset cursor position,
    selection, un-/redo stack etc.

 *Resize policy changed:
    When the main window is resized, only the editor
    will occupy any additional space (it will not
    resize the script list on the left anymore).

 *DND support:
    Drop a file with the extension "rxdata[2]" on
    the editor widget to open it.

 *Persisten settings:
    Things that are preserved between executions:
    Window size, opened file, file chooser directories.

 *File chooser remembers directories:
    Separate for opening/saving to archives and
    importing/exporting.

 *Window title shows current archive filename