Split polylines that cross the IDL into lines in the western hemisphere and eastern hemisphere. Modify the primitive and geometry pipelines to handle split geometry.
Merge branch 'master' into xzPlaneSplit

Conflicts:
	Source/Core/GeometryPipeline.js
Keep track of multiple bounding spheres. One for each geometry returned from the pipeline.
Split simple lines using the plane containing the IDL as the splitting plane.
Split triangles using the plane containing the IDL as the splitting plane.
Clean up instance update after splitting geometry.
Clean up copying geometry attribute properties before splitting.
Compute Columbus View/2D bounding sphere from vertex positions projected to 2D.
Merge branch 'master' into xzPlaneSplit
Merge branch 'master' into xzPlaneSplit

Conflicts:
	Source/Scene/Primitive.js
Fix splitting triangles where a vertex position is exactly on the IDL.
Swizzle CV bounding volume center.
Index triangles when splitting instead of copying every vertex on every encounter.
Use scratch varaibles in original wrap functions.
Start fixing failing tests.
Fix Primitive undefined bounding sphere.
Fix remaining GeometryPipeline tests.
Fix GeometryRendering tests.
Fix more tests.
Fix per instance attributes for geometries split by the IDL.