Refactored functions in BruteForceSearch to work with char vectors
Merge branch 'mpi' of github.com:gandalfcode/gandalf into mpi
MPI now works with the tree. Also moved the updating of hmax values in the local tree at the end of UpdateSphProperties, while the update in the ghost tree has been inserted at the beginning of the force loop routines
For the sake of debugging, the tree now recomputes the true bounding box for each cell