Rename and replace RotAutoFxn with typical implementation

[kmjens]

Description

Current implementation or freud rotational autocorrelation module implements a version that uses hyperspherical harmonics. Typically accepted method in literature is inner product of ref and current orientations input in legendre polynomials and averaged over all particles for each timestep

Gromac Implementation

Rotational Correlation Function of Single Particles

Motivation and Context

Rotational Autocorrelation function of particles in flexicles for 1-to-1 comparison to particles in comparable experimental system.