runs with no segfaults.

need to double-check with master output
restructuring of the code to have a consistent framework.

arofile.py replaces multifile.py (soon to be removed, though they are largely the same)

psrfits_tools.py : parses fitsdef.txt to provide a default PSRFITS file (which arofile inherits)

fold.py : generic folding routine. (will replace fold_*py)

aro.py : ARO data-reduction script adapted to new fold.py and arofile.py interfaces

observations.conf : ConfigObj configuration of the observations.
                   this is a central listing of all the observations carried out

observations.py : parse observations.conf and return a useful object of the observations