gam fitting diagnostic for low station count, adding function to collect k-index diagnostics

initial commit, script for gam fitting experimentation - fitting in low stations area

contributions of covariates and methods paper: revisions- major clean up of code and production of figures for submission of revisions

contribution of covariates and methods paper: revisions- breaking down significance and accuracy of LST by month

contributions of covariates and methods paper: slight changes to function script for LST analyses

contributions of covariates and methods: revisions -adding analyses for LST contribution

contributions of covariates and methods paper: revisions-change of residuals in function of elev and use of lattice package

contributions of covariates and methods paper: revisions - addtional improvements to figures (variograms, residuals etc.)

contribution of covariates and methods: revisions-adding summary of variogram param and accuracy summarized by stations

contribution of covariates and method paper: revisions adding figures of variograms and map of residuals