try first simple version on PDE

conf/coupled/electroMechConPDE.conf

src/coupled/MainCoupled.cpp

src/coupled/solvers/SegregatedSolver.cpp

src/coupled/solvers/SegregatedSolver.hpp

src/electrophysiology/assemble/IElphyAssemble.cpp

src/electrophysiology/assemble/IElphyAssemble.hpp