Added consts to function calls related to loading the inv.sigma matrix.

Also changed one variable from being passed as pointer to being passed as reference, according to the Google coding style guide using a reference is preferred for 'input' variables (that don't change), whereas passing pointers is for 'output' variables, i.e. those that are changed by the function.


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/genabel@1723 edb9625f-4e0d-4859-8d74-9fd3b1da38cb