updates for using loadAllCode.R on Windows. Need to copy Eigen_local to Eigen so we can find the include directories.  Also need to copy MyMakevars_template to MyMakevars in the same directory as MyMakevars_template and loadAllCode.R. Then edit that file to change the value of NIMBLE_PKG_DIR to be the full path to nimble/packages, i.e. the directory containing loadAllCode.R