Change vein colors and artifact object descriptions.

- Changes the non-LOS color to TERM_L_DARK and makes quartz TERM_L_WHITE so that quartz and magma stand out. This should help a bit with better visibility. [1786]
- Changes special artifact object descriptions to show the object kind and flavor until it is picked up. Before picking up: "You see a White Jewel." After: "You see the Jewel 'Evenstar' {special}." [1646]
- Sets some fixed flavors for the special artifacts that have descriptions. I did not update the flvr-xxx.prf files.