PR # 242 tracks these changes.

These changes are grouped thematically by their aim to improve the quality of MPoL as a PyTorch library

• improvements to stability of core routines
• aligning core usage patterns with established PyTorch idioms (e.g., prioritizing torch.tensor ahead of numpy.array , thinking about memory locations of arrays during optimization loops) should yield speed and stability improvements
• documentation changes to be up front about how MPoL (at least the core package) is designed to function as an interferometric imaging library for PyTorch, which might lead to further discussions about what is in/out of scope for the core 'plumbing' package, and what might make more sense in visread (pure numpy visibility manipulations and plotting) or another MPoL-dev package (as 'plumbing', to use Git's terminology).