PathSeg interface

> RESOLUTION: Drop the SVGPathSeg* interfaces if Erik verifies
   the use counter values are correct


I'm surprised it is zero - even though the API interface is a bit unwieldy
and has only very basic support from the browsers.

For instance FF and Chrome support pathSegList and animatedPathSegList, but
IE only supports pathSegList and none of them support the
normalisedPathSegList variants.  Which is a pity, because there are a lot
of cool tricks that could be done with a flattened path.


Even if it is extremely rarely used, surely it would be a huge shame to
remove the only easy way to get access to the list of path segments?  Do we
really expect users to write their own d attribute parsers?

Paul