Updated gloom-style game list

-Tremulous has not had development for quite a while (i.e. not even sporadic)
-Trem/Unvanquished are not natural selection inspired.  They derive from gloom (http://www.moddb.com/mods/gloom) which was developed around the same time as ns1, but was not derived from ns1.  (http://tremulous.net/faq/ second question)