I modified VisIt so that it could be built without Mangled Mesa, so that
we can run on newer Ubuntu systems. You will need to rebuild VTK in order
to build VisIt without Mangled Mesa. When built without Mangled Mesa, it
uses OpenGL for off screen rendering on the engine.

I changed the behavior of build_visit so that it now builds visit without
Mangled Mesa unless Mangled Mesa is explicitly specified or if building a
parallel version. This resolves #968.



git-svn-id: http://visit.ilight.com/svn/visit/trunk/src@17388 18c085ea-50e0-402c-830e-de6fd14e8384