Cryodrgn

Minor updates to 0.3.1 software
* New: Additional Jupyter notebook for particles filtering, `cryoDRGN_filtering.ipynb`
* New: `cryodrgn view_config`
* Fix: Compatibility and deprecation fixes with pytorch 1.7 (29), scipy (39), and seaborn (3111efdc4c147716fd34e6a860ddf6d512f17fdb)
* Updated: More functionality for converting to starfiles with `write_starfile.py` (44)
* Performance improvements to `cryodrgn eval_vol` and a minor fix for a corner case (33)
* Note: The logged KL divergence in stdout is no longer scaled by beta, however the default objective is identical

Minor update to v0.3 software:
* New script `write_starfile.py` to save selected particles as a .star file for use in other tools
* Improvements to `cryodrgn analyze`

* New: GPU parallelization with flag `--multigpu`
* New: Mode for accelerated mixed precision training with flag `--amp`, available for NVIDIA tensor core GPUs
* Interface update:
* Renamed encoder arguments `--qdim` and `--qlayers` to `--enc-dim` and `--enc-layers`
* Renamed decoder arguments `--pdim` and `--players` to `--dec-dim` and `--dec-layers`
* Argument default changes:
* Flipped the default for `--invert-data` to True by default
* Flipped the default for `--window` to True by default
* Updated training recommendations in below quick start guide
* Updates to cryodrgn analyze
* More visualizations
* Order kmeans volumes according to distances in latent space (previously random)
* More features for particle selection and filtering in the Jupiter notebook