IElphyAssemble now creates own Discretization

src/coupled/MainCoupled.cpp

src/electrophysiology/MainMonodomain.cpp

src/electrophysiology/MainOneCell.cpp

src/electrophysiology/assemble/IElphyAssemble.cpp

src/electrophysiology/assemble/IElphyAssemble.hpp

src/electrophysiology/assemble/Monodomain.cpp

src/electrophysiology/assemble/Monodomain.hpp

src/electrophysiology/assemble/MonodomainCoupled.cpp

src/electrophysiology/assemble/MonodomainCoupled.hpp

src/electrophysiology/assemble/MonodomainSplitting.cpp

src/electrophysiology/assemble/MonodomainSplitting.hpp

test/coupled/TestDeformedDiffusion.cpp