Depht

This update resolves 45, a DEPhT bug presenting due to deprecation of SeqFeature.strand as of Biopython 1.82.

Thanks peterjc for your quick assistance.

This update fixes a build issue ([Issue42](https://github.com/chg60/DEPhT/issues/42)) where the specified version of SciPy could not be resolved on some systems.

SciPy is no longer required by DEPhT, and the `conda` installation command should work again. This has been tested on recent versions of MacOS (Intel) and Ubuntu.

A helper script was also added (`depht_fetch_model`) to facilitate installation of DEPhT models available in our repository at OSF.io.

Minor updates made in advance of the release of depht-gui, a graphical interface to improve ease-of-use.

added missing dependency `clustalo` to conda recipe; improved documentation for training pipeline

added missing dependency `phamclust` to package

PyPI package now includes the training module, `depht_train`. A single command is all you need to train a complete model for DEPhT!