commit: 619f056b3f39e04e482d04854c1c166de2621d64

commit: 306dc0559ccfbeb2c0ab02843d572bb1f3bf85f6

This makes it possible to define an editable viewport outside of which the
contents are clipped.

One big benefit is that the getrect routine doesn't need to fetch the bboxes
of the shapes inside the viewport. It just needs the svg width, height, x,
y, and parent transform. It's also possible to add an optimized branch if
there is no parent transform specified.

One drawback is that the HTML5 method getBBox() includes the clipped content
in its calculation. That means the user will get scrollbars even though the
[draw svg] is clipping the contents which cause the scrollbars. Hopefully we
can just work around this by adding a "scrollbars" method for canvases to
just turn them off altogether.

Code for an experimental [draw array] is also added here. Combining it with
the viewport of [draw svg] will make it possible to interact with arrays of
widgets without the performance penalty normally associated with mouse
motion on Pd canvases.

Also:
* fixes some display bugs in certain cases for [draw image] and
[draw sprite]
* adds a default png for both [draw image] and [draw sprite] if none are
given

port c6771297b6f03887034c5f121d3dbf701623ab87 from Pd-l2ork: the big Vanilla forward port won't compile without this commit

added updated help files for pdinfo, classinfo, and canvasinfo (by Jonathan Wilkes), merged patch by Jonathan Wilkes for the search-plugin.tcl with additional enhancements for tab/focus.