0.4.0

This is mainly a bug-fix release.

• The incomplete simplification problem for Fock drudge is fixed. Thanks to Ethan Qiu for pointing this out.
• The incompetent script for running Spark inside SLURM is removed and got improved in the separate spark-in-slurm project.
• Spin-1/2 particle-hole drudge now has explicit orbital range sizes. Thanks to Roman Schutski for fixing this.