moving development to 500lines repo
added author line to README.md
some cleanup and documentation
make changes suggested by @EkkiD, add some other comments, small cosmetic changes
added diagram and explanation of one of the ellipse cases
fix incorrect implementation of Ellipse.signed_distance_bound for internal points
added explanation for internal-point bound, simplified the code by reducing call to ConvexPoly
add support for hex specification
fix bug in transform from typo
add examples
add stub definitions to base abstract class Shape
fix typo spotted by @EkkiD
raise internal error if quadratic() fails due to no real roots
replace Vector.union with AABox.from_vectors as @EkkiD suggested
For didactic purposes, define a base class SceneObject from which Scene and Shape derive.
Restructure contributor table.

- Add 'Online' column to provide space for contributors to represent
  themselves however they would like.
- Move Twitter handles into 'Online' column
Merge branch 'master' of github.com:cscheid/500lines into cscheid-master

Conflicts:
	README.md
Merge branch 'cscheid-master'
Fix conflict in README