QColorDialog should allow name input

The QColorDialog is currently limited to HTML hex names such as #aabbcc, a regular expression is in place to restrict other output. It would be nice if a color names such as "red" are allowed (which could possibly be translated to hex codes when the field focus is lost).

Possible (new) flow:

1. Type name "red".
2. When the name "red" is complete, change the active color name to "#ff0000" (just like the color is currrently name is changed to #f00 or #ff0000).
3. On losing focus, change the displayed HTML color to the hex code (#ff0000) for valid names. For invalid names, leave the text in the field but leave the original color as result (just like it is currently done for "#ff").