Resolves

Resolves #455

Proposed Changes

This PR makes two changes (which I will gladly separate if needed!):

• It re-annotates, and changes some of the variable names used in, the convex hull calculation code for _getConvexHullPointsForDrawable. This should make it a bit clearer to understand.
• It removes the dependency on, and use of, hull.js. In discovering how the hull algorithm works, I have confirmed that the hull it generates is already convex, and thus there is no need to bring in an external dependency to make sure it's extra-convex.

Reason for Changes

These changes make the codebase more friendly to those looking over it for the first time.

(Also, cwillisf, I couldn't find a description of this algorithm anywhere in Numerical Recipes. How could you lie to me like this 😛)