Moved the python environment into 'tools', added Project object in the python environment alongside minor changes, created some scripts to test the environment, and changed make_dot function in topology.ml such that it removes the path of a file before using it as graph name.

Added tools/test/skeleton to test gg and gg-deco. Made also small modifications to make_dot (in topology.ml)

Added an error message when neato doesn't work (when using "gg UDG -du|-dur ...") that is affected by --silent (aka. -s)

Debugged, renamed CommomGraph ClassicGraph, placed all the UDG utils from RandomGraph into a new module, enhanced "gg <command> -s" such that is has effect on warnings, removed "rand" function

Added comments, enhanced 'gg -h', changed some names, replaced an UDG tool function with another, and other minor things.

Added GraphGen to dune. The command is gg. Also added some comments to some .mli files, and reorganized a bit the functions.

Added the tool genGraph, to create .dot graph files (random ones or not, depending on the graph type).

Fix: take into account in dot.ml the change in Topology done in #e76aa9be

where a weigth label has been added

Basically, the idea is to parse the result of the registred ('s ->
string) function.

For instance if  the user define 'v and 'v printer as follows:

 type state = { a : int ; b : float }
 let state_to_string s = Printf.sprintf "x=%d y=%f" s.v1 s.v2

pid_x and pid_y will be used as output var names in the RIF outputs.

If the user provide no name:
 let state_to_string s = Printf.sprintf "%d %f" s.v1 s.v2

some names will be invented (pid_v0 and pid_v1)

All the get_* functions (that are of no interest for users) are now in
the Register module.

Things that are currently broken:
- the ability to init vars in the dot
- controling the name of local vars in the rif output

The idea is to use the Obj module (arg !!!), which is safe thanks to
the fact that there is now only one register function, which forces all the
'v to be bound to the same type.

But I bumped into the "value restriction" limitation
https://stackoverflow.com/questions/22507448/the-value-restriction

Indeed, I need to store functions of 'v in some tables (or references),

And tables are necessaryly weakly polymorphic !

https://v1.realworldocaml.org/v1/en/html/imperative-programming-1.html#side-effects-and-weak-polymorphism

Indeed, by using the Env.nset and Env.nget defined in
0d6575a7 a pb that was hided by the
use of Env.set and Env.get was triggered.

The bug was that variables initialisations were done several times.

In sasa.ml, the way I was updating the Env.t by iterating on the
variables was forcing to "close" expressions that were calling init
functions.

More precisely, they were not consistent by the behavior of -custd mode.
Indeed, It was returning the values of variables after the step is performed.

In the custom demon mode, sasa returns Enab and variable values before
the Activate is computed by the demon.

Chosing one behavior or the other is arguable ; the main advantage of
this choice is that we don't miss the initial values.