Changes since 1.5.1:

• Add hpmc/sphere/orientable to HOOMD schema.
• HOOMD schema 1.3
• Documentation updates
• The length of sliced HOOMDTrajectory objects can be determined with the built-in len() function.
• Silence numpy deprecation warnings
• Add pyproject.toml file that defines numpy as a proper build dependency (requires pip >= 10)
• Reorganize documentation
• Include sys/stat.h on all architectures.
• Close file handle on errors in gsd_open.
• Always close file handle in gsd_close.