converging, but not quadratically
remove back up file
add flag for new cornea models
new rudimentary elastic and viscoelastic isotropic models for the cornea
moved files to cornea_models directory
Clean up code a little. No substantive changes to algorithm.
initial stab at isotropic cornea model
bond (chain) potentials for cornea model
small changes
still not converging quadratically
edit makefile
