added function name
first attempt at adding partial deriv code
partial derivative function complete for gaussmf
incorporating PR feedback
partial derivative for gbellmf added
Merge remote-tracking branch 'origin/mf_partial_deriavtive' into mf_partial_derivative
wanted to bring the local inline

emote-tracking branch 'upstream/master'
incorporating PR feedback
partial derivative for gbellmf added
Merge branch 'mf_partial_derivative' of https://github.com/twmeggs/scikit-fuzzy into mf_partial_derivative
Corrected partial derivative calculations, added derivative calculation for new membership functions, added testing
removed print statement in test
Merge pull request #20 from twmeggs/mf_partial_derivative

FEAT: Partial derivatives of fuzzy membership functions