lmfit/lmfit-py 0.9.9

This release provides a few small but important changes compared to 0.9.8: asteval is now required as a separate install -- a copy is no longer included in lmfit. This makes it easier for asteval developments to happen independently from lmfit. the formatting of floating point numbers in the fit report is now better, fixing at least one bug where the values reported were truncated and incorrect. prefixes of Model components can be changed after the model is created. saving models and modelresults can now include user-specified data (as long as it can be converted to json!)