v0.2.0

BIG CHANGES:

IPW all moved to zepid.causal.ipw. zepid.ipw is no longer supported

IPTW, IPCW, IPMW are now their own classes rather than functions. This was done since diagnostics are easier for IPTW
and the user can access items directly from the models this way.

Addition of TimeVaryGFormula to fit the g-formula for time-varying exposures/confounders

effect_measure_plot() is now EffectMeasurePlot() to conform to PEP

ROC_curve() is now roc(). Also 'probability' was changed to 'threshold', since it now allows any continuous variable for
threshold determinations

MINOR CHANGES:

Added sensitivity analysis as proposed by Fox et al. 2005 (MonteCarloRR)

Updated Sensitivity and Specificity functionality. Added Diagnostics, which calculates
both sensitivity and specificity.

Updated dynamic risk plots to avoid merging warning. Input timeline is converted to a integer (x100000), merged, then
back converted

Updated spline to use np.where rather than list comprehension

Summary data calculators are now within zepid.calc.utils

FUTURE CHANGES:

All pandas effect/association measure calculations will be migrating from functions to classes in a future version.
This will better meet PEP syntax guidelines and allow users to extract elements/print results. Still deciding on the
setup for this... No changes are coming to summary measure calculators (aside from possibly name changes). Intended as
part of v0.3.0

Addition of Targeted Maximum Likelihood Estimation (TMLE). No current timeline developed

Addition of IPW for Interference settings. No current timeline but hopefully before 2018 ends

Further conforming to PEP guidelines (my bad)