Iscc-core

- Added warning on non-standard options
- Added multiformats support
- Added uri representation
- Removed redundant cdc_avg_chunk_size option
- Updated codec format documentation

- Added conformance tests for all top level functions
- Added conformance tests to source dir
- Added conformance module with `selftest` function
- Changed gen_image_code to accept normalized pixels instead of stream
- Changed opts to core_opts
- Removed image pre-processing and Pillow dependency
- Fixed readability of conformance tests
- Fixed soft_hash_video_v0 to accept non-tuple sequences
- Updated example code

- Add dotenv for enviroment based configuration
- Cleanup package toplevel imports
- Return schema objects for iscc_code and iscc_id
- Exclude unset and none values from result dicts
- Add support for multiple code combinations for ISCC-CODE
- Add support for ISCC-ID based on singular Instance-Code
- Add initial conformance test system

- Show counter for ISCC-ID in Code.explain

- Fix documentation
- Change metahash creation logic
- Refactor models
- Add Content-Code-Mixed
- Add ISCC-ID
- Refactor `compose` to `gen_iscc_code`
- Refactor `models` to `schema`

- Simplified options
- Optimize video WTA-hash for use with 64-bit granular features