Restructure and Expand

Changes:

• restructured directory and node tree, so they are easier to read
• added 2D shape support and operations
• expanded on examples with the addition of RayMarching

Full Changelog: v1.0.0...v1.1.0

10 shapes

This release includes these SDFs:

box
box frame
torus
capped torus
cone
cylinder
infinite cylinder
chain link
round box
sphere

It also contains an SDNode abstract class, for fast creation of new shape Nodes.