[swfmill] SVG support committed

[Ralf Fuest]

Hello Mark,
I've added a attribute to the clip tag that allows to define which
elements are exported (turned into symbols).

<clip id="foo" import="bar.svg" export="none"/>
Creates a foo symbol only.

<clip id="foo" import="bar.svg" export="groups"/>
Creates a foo symbol and symbols for all groups.

<clip id="foo" import="bar.svg" export="all"/>
or <clip id="foo" import="bar.svg"/>
Creates symbols for everything.

Does this fulfill your feature request or did you think about something
else?

Ralf

> Sorry, it seems like it really is my file. Inside the groups were
> paths, which are turned into symbols, too.
> So, as a feature request, could we have an option to only turn (named)
> groups into symbols, and paths and such into shapes?
> 
> Mark