Synfig Animation Studio

Committed in r2382.

I agree that to keep a consistent, understandable GUI some care must be
given to its design, and we should avoid plastering buttons all over it.

The reason for creating my own button icons is that the standard icons
don't appear to have icons for the "previous frame" and "next frame"
functions, only for the "jump to start" and "jump to end" functions. To
keep the four icons consistent, I created all of them. The Tango style
appears to have the same problem.

The patch looks fine. I've applied it and works ok.
Anyway before send it to svn I would like to think carefully how should
the main window look after add this and other patches.
I would like to add the play button and some buttons for the onion skin,
for the show hide ducks, etc...
I think that rework need a forum post or some other discussion in the wiki
or similar, before to apply this nice one.

Also I would like to thank you how simple and interesting is the code you
wrote because it motivates and help me to add more features to the main
window..

Last thing. I would be safer to use the tango style for those seek
buttons. That would make the interface more consistent with the rest of
icons. See them here:
http://tango.freedesktop.org/images/2/20/Tango-feet.png