[PD] More data structure/svg junk

Check it out: http://www.jonathanwilkes.net/more-ds.webm

• transformations with a matrix

• svg path support for all drawing commands

• everything plays nice with Pd's subpatch x/y-range and size (not sure about margins), making it almost like an svg viewport (without clipping, unfortunately)

Finally-- I'm also working on a patch that will instantiate certain scalars just by typing the struct name in an object box.  This means people will be able to use data structures for simple (or even complex) prototyping without having to send a pointer anywhere.  If you're just using a single scalar like my demo, you could just as easily send methods to the parent [draw] objects.  (Though if you understand how pointers work it can be handy.)

Problems

• getting the bbox for a path is _hard_.  I can't figure out a good way to cache it without requiring the user to send a message.
• matrix transformations currently do an end run around all of Pd's glist_xtopixels/basex junk and send directly to tkpath.  This makes it way too complex to do stuff like figure out the center of a rotation.  I don't know a good way to deal with this, other than giving a high level interface for translation/rotation/etc.

-Jonathan