fixed memory problems
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
