MAINT: if something has the __call__ attribute, then it is callable
Merge pull request #161 from andyfaff/callable

MAINT: if something has the __call__ attribute, then it is callable
ENH: adding differential evolution as a fitting method
MAINT: include _differentialevolution.py in source, not present in scipy until 0.15
avoid adding dict keys and list
Merge branch 'master' of github.com:lmfit/lmfit-py
Merge pull request #160 from newville/master

Make a separate class for CompositeModel, simplifying Model, and supporting add, subtract, multiply, and divide for Models
Merge pull request #162 from andyfaff/diffev

ENH: adding differential evolution as a fitting method
updated doc/example for composite model
DOC: lmfit.Parameters, improving docstrings
PEP8: lmfit.parameters, removed trailing spaces
DOC: lmfit.minimize, lots of docstrings added/updated.
DOC: lmfit.minimize, doc amendment
DOC: lmfit.minimize, changed backticks to single quotes
DOC: THANKS.txt, adding myself
MAINT: lmfit.minimize, deprecating lmfit.minimize.Minimize.lbfgs
Merge pull request #164 from andyfaff/ParametersDoc

DOC: lmfit.Parameters, improving docstrings
Merge pull request #166 from andyfaff/thanks

DOC: THANKS.txt, adding myself
Merge pull request #165 from andyfaff/minimizedoc

DOC: lmfit.minimize, lots of docstrings added/updated.
Merge pull request #167 from andyfaff/deprecate_mini

MAINT: lmfit.minimize, deprecating lmfit.minimize.Minimize.lbfgs.