* Fonts: bound font-controlled work in enumeration, outlines and carets
An embedded font could make each lookup do far more than real fonts need:
- enumerating a collection read up to 256 faces times 1024 named instances,
each then built with its own shaper; now 4096 per file across all faces,
with a set for the duplicate-style check instead of a scan;
- composite and VARC glyphs could expand one dense outline without limit,
and the outline cache only counted entries; outlines now stop at 32768
path elements (drawing nothing past it) and the cache is also bounded by
the elements it holds;
- the 64-caret limit applied after filtering, so a ligature lookup could
read every caret record; it now applies to the records read.
* address review: bound thread-local glyph cache by path elements