Comment 16 for bug 692582

New version attached, renamed 'Color Markers' and modified according to comment #14 (except the invert option which is implemented as a boolean option).

I've tried to keep how the 'none' attribute is handled (in the original extension 'none' values are not overwritten), but had to adapt the extension a bit:
1. If the marker has a 'none' fill attribute and the first tab is used with a 'solid' marker type, the extension doesn't apply the fill and fill-opacity attributes.
2. If the marker has a 'none' stroke attribute and the first tab is used with a 'filled' marker type, the extension doesn't apply the stroke and stroke-opacity attributes.
3. In all other cases, all color and opacity attributes are modified.

Comments are welcome!