Spring RTS Engine

Highlights features with metal in the metal-map viewmode:

http://trepan.bzflag.bz/spring/gui_metal_features.lua

P.S. I'll probably add markers to the minimap as well

P.P.S. This uses the Spring.GetAllFeatures() call, which
can be slow. The slowdown will only occur when viewing
in metal-map mode. I may code an alternate method later.

Image:
http://trepan.bzflag.bz/spring/metal_features.jpg

This looks useful!