Integrate Oscar's latest optimizations, add --profile option to find-orientations, start performance analysis

These changes have been validated by comparing before/after results of the multiruby dataset. This PR includes:

* A numba-optimized version of angularPixelSize
* A vectorized simulateGVecs
* A new --profile option to the hexrd find-orientations command
* A first optimization based on the profile measurement, rewriting a special-case 2D version of np.meshgrid.
* A few more optimizations that restructure the paintGrid code to be more vectorized.