Add GL traits for Double precision Eigen types.
Add GL traits for Double precision Eigen types.

tschmidt23/Pangolin,wxdzju/Pangolin,renzodenardi/Pangolin,mp3guy/Pangolin,tschmidt23/Pangolin,stevenlovegrove/Pangolin,randi120/Pangolin,mp3guy/Pangolin,tschmidt23/Pangolin,stevenlovegrove/Pangolin,wxdzju/Pangolin,renzodenardi/Pangolin,mp3guy/Pangolin,randi120/Pangolin,stevenlovegrove/Pangolin