Crate all_is_cubes_port

Data import and export between all_is_cubes types and other data formats.

Currently supported formats:

Format	Extension	Import	Export	Caveats
All is Cubes native	.alliscubesjson	Yes	Yes	Version compatibility not yet guaranteed.
MagicaVoxel .vox	.vox	Yes	Yes	Materials, scenes, and layers are ignored.
glTF 2.0	.gltf	—	Yes	Textures are not yet implemented. Output is suitable for rendering but not necessarily editing due to combined meshes.
STL	.stl	—	Yes	Meshes are not necessarily “manifold”/“watertight”.

Modules

• file
  File system abstraction, for importing data that does not necessarily live on the file system that std::fs accesses.
• gltf
  Export to the glTF 3D file format.

Structs

• ExportSet
  Selection of the data to be exported.
• ImportError
  Fatal errors that may be encountered during an import operation.

Enums

• ExportError
  Fatal errors that may be encountered during an export operation.
• ExportFormat
  File formats that All is Cubes data can be exported to.
• ImportErrorKind
  Specific reason why an import operation failed. Always contained within an ImportError.

Functions

• export_to_path
  Export data specified by an ExportSet to a file on disk.
• load_universe_from_file
  Load a Universe described by the given file (of guessed format).