Bug fix in density correct terms. Multiphase velocity BC has been simplified for this early stage of the development.

Implements surface tension following Hesam's code. Also corrects uninitialized variables in MultiphaseCumulantLBMKernel::findNeighbors . This might have influence on the contact angle. Initialization is now set to zero!

Implements pressure and stress correction for multiphase model with density contrast. Pressure is regularized and hence different from the form used by Safari and Fakahri. Surface tension is not implemented.

Implements cumulant phase field function and a passive incompressible momentum equation. The phase field is only coupled to the fluid velocity but there is no featback to the fluid. Only as a starting step for further developments.

 - metis: do not pass -O3 flag on msvc compiler, as this flag is ignored anyway. Instead of /w pass w0, which is equivalent to /w.
 - RheologyK17LBMKernel: A and B are also defined in D3Q27System.h. Therefore to not hide this declaration they are renamed to A_ and B_
 - additional small clean ups...

Exchange DEPENDS (which links everything private) variable with PUBLIC_LINK and PRIVATE_LINK. Therefore VirtualFluidsCPU is linking everything public know. Everything else is still linking private.

Changed typedefs to using.