Add log beam ratio storage to doublebeam, use in R calculation

* Add memoized computation of log (beam1 / beam2) to doublebeam.
* Use this in numberCountsDoubleLogNormal::getR (array version)
  which allows a log to be removed from the inner loop.
* Not tested yet, but it does compile.
Add HDF5 requirement.
Use monolithic calls to getR when doing edge integrations in 2D case

* Rather than calling getR for every edge x, y value in PDFactoryDouble
  get blocks of them and integrate those.  This is to avoid
  getR overheads.  This involves changing the REdge variables setup a bit.
Add precomputation of 1/f2, log(f2) to getR for 2D model.
Slight performance tweaks, bump version number

* It turns out to be much faster to test if f2work_inv is zero
  than to test the sign variable f2work_sgn.
* Replace unsigned char usage with unsigned int -- again, very
  slightly faster.
* Bump version number to 0.4.1, since the R computation speedup is
  significant (from 14 sec to 8 sec in tests on a typical problem
  size, and with filtered beams)
Change RFlux[12] to Flux[12] in output HDF5 for consistency with 1D version.