make it possible to save tiled clone settings

[SCYG]

Right now if you want to make a series of tiled clone groups with different settings, you have to record the settings manually - and that's potentially a whole lot of settings. It would be good if there could be an option to save the settings to a file and then load them again when needed.

[su_v (suv-lp)]

See also a recent attempt for refactoring the 'Tiled Clones' dialog:
<http://wiki.inkscape.org/wiki/index.php/Tiled-Clones>

Related discussion in inkscape-devel:
<http://thread.gmane.org/gmane.comp.graphics.inkscape.devel/34785>