Support binary STL export.

[mortenbekditlevsen]

I'm not strong in Swift's pointer manipulation, but this seems to do the trick. :-)

[codecov[bot]]

Codecov Report

Merging #105 (de8055d) into main (14f0342) will increase coverage by 0.15%. The diff coverage is 98.24%.

@@            Coverage Diff             @@
##             main     #105      +/-   ##
==========================================
+ Coverage   79.20%   79.35%   +0.15%     
==========================================
  Files          29       29              
  Lines        7113     7170      +57     
==========================================
+ Hits         5634     5690      +56     
- Misses       1479     1480       +1     

Files Changed	Coverage Δ
Sources/Mesh+STL.swift	98.80% <98.24%> (-1.20%)	:arrow_down:

[nicklockwood]

Looks great - thanks!