Modified FDTD_GPU.cu, FDTD_common.hxx, test.cxx.  FDTD_GPU.cu now uses Debye-model dispersion. Phase measurements of the far field is now used in error calculation. One is also able to change the number of optimization patches (resolution of the optimized image) by changing the parameter numpatches in both test.cxx and FDTD_common.hxx.