[BUG] NiftyReg doesn't deal with spaces in file names
As with amap, see https://github.com/SainsburyWellcomeCentre/amap-python/issues/56
I think this can be solved by just adding quotes to the paths sent to niftyreg.
This is also an issue if brainreg is installed in a directory with spaces, as the path to niftyreg is used as a command to bash/cmd.
Fixed in 649a91540c3918a755438cacc9932193a7ef9d5d
Not fully fixed - output files are incorrectly named.
Closing this because I can't see any issue with the output filenames when the input has a space in the name. Can always reopen if we notice something.