Swiftsimio

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Backwards-compatibility update:

+ Write "NumFilesPerSnapshot", "NumPart_ThisFile", and "MassTable" to snapshots.
+ Added ability to write extra items to the header.

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Minor bugfixes and improvements:

+ Added the MaterialID field
+ Changed internal energy units to be correct (energy per unit mass).

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Documentation update!

+ Includes significantly more documentation for how to create initial conditions
files with `swiftsimio`.
+ Minor bugfixes throughout.
+ Added `swiftsimio.validate_file` to validate your dataset is a SWIFT output
file before reading.
+ Added a number of metadata properties to the reader for pretty-printing code
information: `compiler_info`, `library_info`, `hydro_info`, `viscosity_info`,
`code_info`
+ Added ability to automatically generate smoothing lengths for gas datasets
in the writer.

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First writer update:

+ Implements writer functionality. This allows for an object-oriented API to be
used to create SWIFT IC files.
+ Compatibility changes in the reader to work with self-generated initial
conditions files.
+ Minor bugfixes.

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Fixed a minor packaging bug.

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First minor revision:

+ Fixes a minor packaging issue
+ Implements some boilerplate for upcoming features