Fix: the Register.diameter returned the links number (introduced in sha:40eece7c)

- add sub_tree_size, parent, is_in_tree, is_out_tree
- fix height (was only working for out-trees)
- a predessors to Topology.t
- refactor a lot of strange things in the code
  - in the use of hashtbl in particular

Fix: the seed init should be done *before* the process init (otherwise there is no randomness in the initial configuration!)

Fix a bug in the RIF data output: enable and trigger actions order was not the same in value and in the declaration

to try it :

cd test/coloring
echo "(* Do not edit me ; edit mv_hook.ml instead! *)" > include.ml
echo "#use \"../../tools/rdbg4sasa/daemongui.ml\";;" >> include.ml
make grid4.ml
ledit rdbg --missing-vars-last  -env "sasa grid4.dot -custd"