Account for varying toe marker positions

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Feature Request

Feature Description
Account for the various TOE marker positions used by each lab.

Currently the shape model fitting process assumes that the TOE markers are placed between the 2nd and 3rd metatarsal heads. Some labs place the foot markers proximally, some place them only on the 1st or 5th metatarsals. The shape model should be able to account for this. C3D-Parser marker-set can define which placement the lab is using, but the shape model may need additional markers to be able to align with each of these cases.