[Mne_analysis] Change fmult in mne_make_movie

[Tsung-Ren Huang]

Hello MNE experts,

I'm generating quicktime movies from .stc files using mne_make_movie.

In mne_analyze, I can change fmult among with fthresh, fmid, and fmax.
However, mne_make_movie does not offer the --fmult option.
I then tried the --scaleby option, which doesn't seem to work
without --label specified.

I wonder if there's a simple way for mne_make_movie to change the
scale factor, as in mne_analyze!?

Thanks in advance!
Tren