Split /src/extras/core/Curve.js to
/src/extra/curves/*

LineCurve
QuadraticBezierCurve
CubicBezierCurve
SplineCurve
EllipseCurve
ArcCurve
LineCurve3
QuadraticBezierCurve3
CubicBezierCurve3
SplineCurve3
ClosedSplineCurve3

WebGLRenderer3: Added normals, programs cache, fallback for program compiled with errors and basic support for ShaderMaterial.

The previous boolean type allowed for either a 0 or a 1 pixel overdraw
for fixing antialiasing gaps in CanvasRenderer. I've found the best
value to be 0.35, though this may be browser/gpu specific. Should be
backwards compatible.