Add "CQS VS test samples" data to "colour.quality.datasets" sub-package.
Implement initial "colour.quality.cqs._vs_colorimetry_data" definition.
Implement "colour.quality.cqs._colour_quality_spaces" definition.
Implement "colour.quality.cqs.colour_quality_scale" definition.
Add unit tests skeleton for "CQS" computation.
Fix import error.
Ensure docstrings consistency.
Add "Travis-CI" notifications to "Slack".
Implement "__pow__" magic method for "colour.SpectralPowerDistribution" class.
Implement "__pow__" magic method for "colour.TriSpectralPowerDistribution" class.
Fix doctests for "colour.SpectralPowerDistribution" and "colour.TriSpectralPowerDistribution" classes.
Fix issue in "CQS" "RMS" computation.
Update "colour.quality" sub-package imports.
Update references.
Fix import error in "colour.quality.tests.tests_cqs" module.
Fix doctests of "colour.colour_quality_scale" definition.
Format code in "colour.quality.cqs" module and related modules.
Fix incorrect "colour.quality.cqs.VsColorimetryData" namedtuple name.