Pass some parameters to FIT instead of read from options to do it more general and use it in RUBIX. Delete unnecessary params in Samples Save

Deleted bedpostx_multigpu_SGE because now the MultiGPU version in SGE will be controlled by fsl_sub and NGPU parameter in bedpostx_gpu

Changed the way of divide set of voxels (before by slices). Now in X parts each one divided in subparts of a maximum number of voxels that are sent to the GPU in a iteretive fashion

Deleted splitter_gpu.cc splitter_multigpu.cc because now the division of slices and voxels is make inside scripts and xfibres_gpu.cc