add Glyph.appendContour method for defcon API compat

[anthrotype]

#41

I am sure there are more missing methods, but we can add them as we need.

[codecov-io]

Codecov Report

Merging #48 into master will increase coverage by 0.13%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #48      +/-   ##
==========================================
+ Coverage   71.82%   71.95%   +0.13%     
==========================================
  Files          19       19              
  Lines        1072     1077       +5     
  Branches      159      160       +1     
==========================================
+ Hits          770      775       +5     
  Misses        258      258              
  Partials       44       44

Impacted Files	Coverage Δ
src/ufoLib2/objects/glyph.py	67.36% <100%> (+1.17%)	⬆️
src/ufoLib2/objects/point.py	90.9% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6cbb279...f08f209. Read the comment docs.