QColor does not recognize any variant of the olive color name, and more generally could be much more robust

QColor doesn't recognize either "olive" or "Olive" as a valid color name.  this is one of the most basic colors, part of the original HTML 16 colors, defined as 808000 - a basic nodal point in color space (basically a version of dark yellow, but much more familiar as olive).

Users of our app enter color names for lines in a graph, and this is a good color to have available.

Also, it would be great if QColor could recognize "Blue" in addition to "blue", again because users are entering these names, and being more robust would be better.  Likewise, some colors require CamelCase such as ForestGreen - would be great to allow forestgreen as well.  Case really shouldn't matter.

The docs point to this page: https://www.w3.org/TR/SVG/types.html#ColorKeywords but the colors there are all lowercase..