color: move 'debugcolor' into the 'debugcommands' modules This is the last bits we needed to move out of the extensions. 'hgext/color.py' now only contains logic to changes the default color behavior to 'auto'. However, more cleanups are on the way and we need to document the new config directly in core.

merge with stable

color: rename '_styles' to '_defaultstyles' for clarity This should make it clear the dict is only used for new config. Extensions should not modify it directly anyway since we have 'extraloader' logic for loading '_styles' too.

color: move 'styles' definition on the 'ui' object Same logic as for '_terminfoparams'. The content depends on the config so it should be specific to each 'ui instance.