NEW: wrote sct_fmri_compute_tsnr.py python script to replace sct_compute_tsnr.sh shell script (issue #193)
NEW: wrote sct_fmri_compute_tsnr.py python script to replace sct_compute_tsnr.sh shell script (issue #193)

Former-commit-id: 28ce00c7b681399d522ccf861880f692fd027547 [formerly 7f684af402e80a8142e46921fdab5bc903a2d33d]
Former-commit-id: 84a086b3c2f7164ec2c3d182aa05047b392ced00
Former-commit-id: 6577a8c74b34dcb532fc834635914ffa953d14fa
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox