PR: Implement support for "Leica L-Log" log encoding curve.

[KelSolaar]

Summary

This PR implements support for the Leica L-Log log encoding curve.

References #980.

Preflight

Code Style and Quality

• Unit tests have been implemented and passed.
• Mypy static checking has been run and passed.
• Pre-commit hooks have been run and passed.
• [N/A] New transformations have been added to the Automatic Colour Conversion Graph.
• New transformations have been exported to the relevant namespaces, e.g. colour, colour.models.

Documentation

• New features are documented along with examples if relevant.
• The documentation is Sphinx and numpydoc compliant.

[nick-shaw]

I may be missing something, but it seems that colour.models.log_encoding(0.18, 'L-Log') works, but colour.models.log_encoding_LLog(0.18) does not.

[nick-shaw]

LLog (encoding and decoding) appears to be omitted from the lists in __init__.py under colour/models and colour/models/rgb.

[zachlewis]

This little OCIO bit works as expected:
!<LogCameraTransform> {name: Leica L-Log to Linear, base: 10, log_side_slope: 0.27, log_side_offset: 0.6, lin_side_slope: 1.3, lin_side_offset: 0.0115, lin_side_break: 0.006, linear_slope: 8, direction: inverse}

[zachlewis]

CONSTANTS_NLOG should be CONSTANTS_LLOG

[KelSolaar]

CONSTANTS_NLOG should be CONSTANTS_LLOG

Thanks, good catch!

Small Horror Story

I wrote the module two times and managed to lose the code failing with git stash fu, the first time it was correct as I remember changing it specifically because the N-LOG one was not consistent.

[KelSolaar]

LLog (encoding and decoding) appears to be omitted from the lists in __init__.py under colour/models and colour/models/rgb.

Good catch, I forgot that we need to explicitly import the transfer functions since I made the typing annotation changes. Before, we were bubbling back up with import *