completed cardiac tissue material model
added some kind of stress potential (T_MN*FMi) to the material properties
removed stress potential again - will do the comjputation explicitly in the respective kernels
removed stress potential again - will do the comjputation explicitly in the respective kernels
added kind of stress-diffusion kernel (at least it would look like diffusion of the 2nd Piola Kirchoff tensor was not included). added registration for all user-created objects
added boring boundary conditions in input file - fill have to add force boundary condition in code now (again: PiolaKirchhoff2nd*GradientDisplacements ...)