Initial commit with stubs.
Add gears.rb (translated from ycad).
Implement Shape.add, .sub, .mul, .extrude, .revolve in terms
of other classes.
Add initialize stub for Circle class.
Add comment for Shape.render.
Fix GearProfile comments.
Add shorter aliases for primitive shapes.
Move Text stub next to 2D shapes.
Add Box stub and base Cube on it.
Translate pedestal example from ycad.
Fix primitive constructor aliases.
Fix method name in pedestal example.
Add stub extension using rice.
Wrap BRepPrimAPI_MakeBox with Box class in _yrcad extension.
Make Box wrapping actually work, including STL output.
Ignore various output files.
Accept String param correctly in shape_write_stl.
Translate OCE Standard_Failures to a Ruby OCEError class.
Implement CSG operations.
Implement Polygon. render method may now return a Shape object,
in which case render is called recursively.