tiny fix in demo_dmtx, as set_size_inches does not tolerate forward=True on my laptop
tiny fix in demo_dmtx, as set_size_inches does not tolerate forward=True on my laptop

nipy/nipy-labs,alexis-roche/nireg,bthirion/nipy,arokem/nipy,bthirion/nipy,bthirion/nipy,arokem/nipy,alexis-roche/nipy,alexis-roche/nipy,nipy/nipy-labs,nipy/nireg,alexis-roche/nireg,bthirion/nipy,arokem/nipy,arokem/nipy,alexis-roche/nipy,alexis-roche/niseg,alexis-roche/nipy,alexis-roche/register,alexis-roche/niseg,alexis-roche/register,nipy/nireg,alexis-roche/register