Minor fix to setup script
Rewrite acceptance fit as a simultaneous fit

Doesn't converge.  Do a 2 step fit, then follow up by the simultaneous
fit.  Hopefully this will have the parameter initial values at the
right place helping it converge.
Remove redundant datahist code
Do 2-step fit before simultaneous fit

1. Fit for Dsπ acceptance with PowLawAcceptance
2. Fit for DsK acceptance with AcceptanceRatio × PowLawAcceptance with
   parameters from step (1) fixed
3. Simultaneous fit for Dsπ and DsK with all parameters free

FIXME: plotting after simultaneous fit is still incorrect
Let rbeta (β for AcceptanceRatio) float
Change DsK acceptance to RooProduct

Earlier I was using my multiplication inside PowLawAcceptance:

  dsk_acceptance = PowLawAcceptance(dspi_acceptance,
                                    'dsk_acceptance', ratio)

Now use RooProduct instead:

  dsk_acceptance = RooProduct('dsk_acceptance',
                              'DsK Acceptance with ratio',
                              RooArgList(dspi_acceptance, ratio))
Change rbeta (β for AcceptanceRatio) starting value
Print variables before DsK fit
Clean up option parsing
Simultaneous Dsπ and DsK acceptance fit works!

1. Because of Python scoping rules in loops, DsK dataset was empty
2. Add dataset print outs

Reminder to self: always print every thing
Tiny clean up
Fix plotting in ltFit.py
Minor clean up of plotting script