Increase version number
Missing CHANGELOG
(transplanted from 3844a4189bd85b13ab36217f1e0aa59913220d74)

--HG--
extra : transplant_source : 8D%A4%18%9B%D8%5B%13%AB6%21%7F%1E%0A%A5%99%13%22%0Dt
Prepare release 3.0.1
Added tag 3.0.1 for changeset cece4b463769
Increase version number
Make a copy of the payment iterators

We copy the iterators created by groupby in order to prevent consumption of the
underlying iterator.

issue3660
review3321002
(transplanted from f6a75fb9052b5a3650a4230233d4dd6d478099b5)

--HG--
extra : transplant_source : %F6%A7_%B9%05%2BZ6P%A4%23%023%D4%DDmG%80%99%B5
null merge from 3.0
Improve setup.py to allow dev publication

issue3436
issue1891
review2441002
Do not create a letter when dunning amount == payment amount

review4351002
issue3760