The layers list and the Dopesheet channels now show color swatches for both the
stroke and fill colours now. This is useful when you've got layers that only
use either/or.
* Currently, these only get shown if the relevant opacity setting is high enough
for that aspect to contribute to the result.
* The sizing of these items could do with some more tweaking (especially in the
Dopesheet), as these may now be too small to accurately see and/or interact with.
* There are some potential issues when using near-gray (or actually, colours similar
to the list backgrounds, but that issue exists in other areas of Blender anyway.
(NOTE: At this stage, these changes are still experimental, and not for 2.73 yet)
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