* Add function `modelToExpr(model, impacts)`, returning expression with background activities replaced by the value of each impact.
0.0.4
* Added button for **exporting** data as csv on any **Dataframe** in stats tools * **actToExpression** now replaces fixed params by their default values, providing simplified models. * **newSwitchAct** can take custom amounts (not only '1') by providing tuple (act, amount)