Build an ensemble piv solver based on PIVLab and Carl's work
See Carl's implementation here: https://code.usgs.gov/cjl/trivia/-/blob/main/code/ensemblePiv.m
Some other ideas:
- The inner loop maths can probably be vectorized a fair bit
- If we split the frame pairs up a priori, then we can skip the loop, and instead pass jobs to workers in a threadpool.