__init__
MamboMBFits:
MamboMBFits.py
DES: Instanciation of a new MamboMBFits object.
INP: (str) mamboName = name of the Mambo file
(str) mbName = name of the MB-FITS file
in both cases, the .fits extension is appended if not present
HIS: FS041210 also handle names that already contain .fits