After this commit the tree height is choose at execution time.
This is a simple parameter given to the tree (FOctree) constructor. (Instead of a template) git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/scalfmm/scalfmm/trunk@103 2616d619-271b-44dc-8df4-d4a8f33a7222