* updated the voxel_lm code to work with R 3.*.* As of R 3.0.0, the Fortran function ch2inv is deprecated and defunct, and it was used in the voxel_lm function. This is now replaced by the Lapack dpotri function. Since Lapack is now used, its library was added to src/Makevars.in.
* also removed some variables that were not used to reduce the number of compilation warnings