Blender Git Loki

Make it optional to track input->output mapping in delaunay_2d_calc.

Some uses of delaunay_2d_calc don't need to know the original verts,
edges, and faces that correspond to output elements.
This change adds a "need_ids" value to the CDT input spec, default true,
which tracks the input ids only when true.
The python api mathutils.geometry.delaunay_2d_cdt gets an optional
final bool argument that is the value of need_ids. If the argument
is not supplied, it is true by default, so this won't break old uses
of the API.

On a sample text test, not tracking ids save about 30% of the runtime.
For most inputs the difference will not be so dramatic: it only really
kicks in if there are a lot of holes.