This PR includes four major updates to the public release of FluTAS:
Fix bug in the calculation of the normal vector calculation (previous version introduces a small error of the order 1e-8 which was anyway reduced by grid refinement);
Improve documentation;
Add the single-phase module;
Re-organize the momentum advection for future sustainable developments (e.g., the source terms of the momentum equation are added in the main program rather than in the rk.f90 routine).
This PR includes four major updates to the public release of FluTAS: