* change functions in levelset/twophaseCoeff
Merge remote-tracking branch 'origin/contactangle' into contactangle
Merge remote-tracking branch 'origin' into contactangle
* add a new example for two-phase Couette flow
*Xianmin: add a new example
*change the checktwophaseflow function and the pressure function
Merge remote-tracking branch 'origin' into contactangle
*fix bug?
Merge branch 'contactangle' of https://github.com/liangzhangleon/dropscontactangle into contactangle