MNT: Initial copy of Chris Rorden's gpu_test

gpu_test/ptest/bedpost.bedpostX/xfms/eye.mat

gpu_test/ptest/masks/1.nii.gz

gpu_test/ptest/masks/10.nii.gz

gpu_test/ptest/masks/100.nii.gz

gpu_test/ptest/masks/101.nii.gz

gpu_test/ptest/masks/102.nii.gz

gpu_test/ptest/masks/103.nii.gz

gpu_test/ptest/masks/104.nii.gz

gpu_test/ptest/masks/105.nii.gz

gpu_test/ptest/masks/106.nii.gz

gpu_test/ptest/masks/107.nii.gz

gpu_test/ptest/masks/108.nii.gz

gpu_test/ptest/masks/109.nii.gz

gpu_test/ptest/masks/11.nii.gz

gpu_test/ptest/masks/110.nii.gz

gpu_test/ptest/masks/111.nii.gz

gpu_test/ptest/masks/112.nii.gz

gpu_test/ptest/masks/113.nii.gz

gpu_test/ptest/masks/114.nii.gz

gpu_test/ptest/masks/115.nii.gz