E57

- Added missing support for original GUIDs member of point clouds.
The breaking API changes for this feature were already part of the last release.
- Allow access to the E57 library version field when reading E57 files.

- Breaking Change: Made GUIDs for point clouds and images optional.
This required changes in the corresponding public structs.
The spec says the GUID for both is required, but the C++ implementation allows to omit it.
Some software (e.g. Matterport) is generating files without them,
so we need to make it optional to stay compatible and read these files.
When creating E57 files, the library still enforces setting the GUIDs.
- Breaking Change: Prepared structs for missing original GUIDs.
This feature was missing and was prepared now to avoid more breaking changes later.
Its not yet implemented and can be added later as non-breaking change.

- Fixed major bug that prevented adding images to E57 files.
Some required property structs were accidentally private.
- Added some C++ utility code to generate test example files using the libE57format library.
- Restructured and extended integration tests to cover more cases.

- Breaking Fix: Added missing implementation for offset in scaled integers.
This required changes in the basic enum for record data types.
- Additional perfomance improvements when reading E57 files.
- Added validation for XML namespaces and attributes when writing E57 files with extensions.
- Added support for optional faster external CRC32 crate.
- Implemented optional size_hint() for reading point cloud iterators.
- Reworked image extraction tool to become a generic E57 unpack tool.
- Very minor improvements to the XYZ-to-E57 tool.

- Breaking: Reworked simple iterator to make it easier to use
- Breaking: Removed simple iterator option to skip invalid points
- Speed up reading E57 files by ~30%
- Added convenience helper functions for point cloud struct
to easily check if it has certain point attributes
- Added simple iterator option to convert Cartesian to spherical coordinates
- Added new E57-to-LAZ example tool
- Faster E57-to-XYZ tool (uses now ryu for float-to-string conversion)
- Added this CHANGELOG.md file

- Breaking: Extended RecordName enum and made it non_exhaustive
- Added missing support for point attribute extensions
- Optimized simple iterator to be ~30% faster