INT: Integration of isoAdvector and supporting material

Community contribution from Johan Roenby, DHI

IsoAdvector is a geometric Volume-of-Fluid method for advection of a
sharp interface between two incompressible fluids. It works on both
structured and unstructured meshes with no requirements on cell shapes.
IsoAdvector is as an alternative choice for the interface compression
treatment with the MULES limiter implemented in the interFoam family
of solvers.

The isoAdvector concept and code was developed at DHI and was funded
by a Sapere Aude postdoc grant to Johan Roenby from The Danish Council
for Independent Research | Technology and Production Sciences (Grant-ID:
DFF - 1337-00118B - FTP).
Co-funding is also provided by the GTS grant to DHI from the Danish
Agency for Science, Technology and Innovation.

The ideas behind and performance of the isoAdvector scheme is
documented in:

    Roenby J, Bredmose H, Jasak H. 2016 A computational method for sharp
    interface  advection. R. Soc. open sci. 3: 160...