[FIX] fixed a bug in the XR2XI routine
[HELP] fixed the help descriptions
[NEW] added unit tests for XR2XI routine
[FIX] bug in the 1D XR2XI functions
[SIMPLIFICATION] got rid of the preliminary limitation of meshes before intersection
[FIX] corrected bug when model DOFs and CArl DOFs are not the same
[ADD] first contributions for the incorporation of LATIN solver