Corrections to 3DMECHTEMPSEMICOND_NAT and 3DSEMICONDUCTOR_NAT
improved numerical differentiation
corrected Jacobian terms for 3DMECHTEMPSEMICOND_NAT
a correction of EQFL, HQFL
some changes aiming to make the newton solver to be more stable
add a sparse GMRES solver to the project
revert to former version (basically)
correct the usage of lambdas to be shared in openmp statement (vtk_cellpolt)