removed paranoid backup from gaussian_process
removed fbar_model and gross_gp from gaussian_process.cpp

also found a bug in how gp::user_predict calculated sigma; fixed that
made indentation consistent in gaussian_process.h
removed unused variable time_dummy_search from gaussian_process.cpp
forgot to update gaussian_process.h on that last change
documented some minor routines in gaussian_process.cpp
added some comments to gp::initialize
removed unused function get_biggest_neighbor from gaussian_process.cpp
removed unused function get_neighbor_range from gaussian_process.cpp
documented the variations on user_predict in gaussian_process.h
some more minor documentation before I start commenting the predict method in gaussian_process.cpp
fixed indentation in gp::predict
commented the source code for predict in gaussian_process.cpp

also: there was an error in the sig_alg code (which sets a value for sigma in the event that the theoretically correct calculation fails to return a non-zero value).  That has been fixed
removed unused actual_gradient routines from gaussian_process.cpp
removed unused user_predict_gradient routine from gaussian_process.cpp
fixed indent in self_predict backend
documented self_predict in gaussian_process.cpp
removed all of the unnecessary n_use variables from the optimize() routines in gaussian_process.cpp
made optimize_grid and optimize_simplex private routines in gaussian_process.h
cleaned up some of the gp::optimize routines