refine_rp_by_lens_finetune(): Fix lensHoriz, lensVert update for negative delta
autorectify(): Measure and print time spent
Autorectify finetune_lens_position(): Reuse portion of shiftmatrix during the local search

This is a major speedup, about 50% boost.
Autorectify finetune_lens_position(): Negative coordinates are illegal condition