IECoreRI renderer now constructs mesh primitives without checking topology
IECoreRI renderer now constructs mesh primitives without checking topology

Previously, when rendering scenes with large amounts of instanced meshes, an inordinate amound of time was being spent in MeshPrimitive::setTopology(). RendererImplementation::mesh() now uses MeshPrimitive::setTopologyUnchecked() to avoid that.

hradec/cortex,lento/cortex,goddardl/cortex,davidsminor/cortex,danieldresser/cortex,davidsminor/cortex,davidsminor/cortex,lento/cortex,appleseedhq/cortex,appleseedhq/cortex,davidsminor/cortex,danieldresser/cortex,hradec/cortex,appleseedhq/cortex,danieldresser/cortex,hradec/cortex,danieldresser/cortex,lento/cortex,goddardl/cortex,goddardl/cortex