Vegas

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Bug fix for situations where the error in the answer
is smaller than 1e-8 times the answer -- ie, unlikely
to affect many existing codes. The old code reported
cumulative errors that were too large. (Thanks to
Gabriele Spada for pointing this out.)

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Minor documentation update; can be ignored otherwise.

- Updates examples to account for changes in mpirun.

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Again a very minor update, to respond to a feature request.

- Adds mpi keyword to Integrator. Setting mpi=False disables mpi support in
vegas even if mpi is available; setting mpi=True (default) uses mpi
automatically (so long as it is installed).

- Improved documentation on the use of C and Fortran with vegas.

- A new section in the tutorial on how to calculate distributions with vegas.

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Very, very minor update.

- Fix compatibility issue with v11 of lsqfit.

- Improved pypi documentation.

- Improved makefile.

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Minor update; minor bug fixes.

- Documentation fixes.

- Fixed bugs associated with parameters minimize_mem=True and beta=0.
These resulted in sub-optimal behavior.

- New timing information in vegas.reporter(). Also flushes stdout after
each iteration.

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Tiny change to test scripts to account for changes in numpy.