Remove all the cruft, calculate mean and STD
Remove all the cruft, calculate mean and STD

Going step-by-step, I'm removing all the (for now) unnecessary functions
to calculate the power spectral density and MTF. They will come back
from MTF2.py, but for now we don't need them.
The script now loads (raw) images from DevWare, calculates the mean
(exposure) and STD and plots these values. Proceeding here to calculate
the MTF and other niceties.

habi/GlobalDiagnostiX,habi/GlobalDiagnostiX,habi/GlobalDiagnostiX