adding support for 2D, NSIDED element type

git-svn-id: svn+ssh://portal-auth.nersc.gov/project/projectdirs/visit/svn/visit/branches/2.7RC/src@21921 18c085ea-50e0-402c-830e-de6fd14e8384
adding support for 3D cylindirical, rectilinear coords quadmeshes

git-svn-id: svn+ssh://portal-auth.nersc.gov/project/projectdirs/visit/svn/visit/branches/2.7RC/src@21922 18c085ea-50e0-402c-830e-de6fd14e8384
Fix SLIVR, introduce Raycasting: SLIVR, more coherent renderer dialog, add support for trilinear interpolation in raycasters.
replace non-standard hash_map with map