The solution we had before worked in most cases but there were some
which caused problems still. This is what HarfBuzz's CoreText shaper
backend does, it uses a CTTypesetter with the forced embedding level
attribute. This fixes the failure case I found that was causing non-
monotonic outputs which can have all sorts of unexpected results, and
causes a crash in Debug modes because we assert the monotonicity while
rendering.

Reduce potential allocation while processing glyphs by ensuring capacity
in the buffer ahead of time and also using CTRunGet*Ptr functions first
and only allocating for those if that didn't work (it should almost
always work in practice.)

Yet another low-hanging fruit

Hi there, this is just a low-hanging fruit and it also prepares the way
for the future 0.15, which removes addStaticLibrary.
Please, let me know what to do on the `// TODO` comments.