*** empty log message ***
variables renaming
remove redundant call to root6() in contactForce()
Adding code from RGViscoelasticityT - errors in compilation
openmp enabled and tested
fixes - code now reproduces DE w/o visco results
added viscoelastic DE option
viscoelastic DE
derive from FSSolidMatT, not NL_E_MatT
put all parameters in one file