- split_* splits on the right-hand side
- full_split_* splits on the both sides
- split functions do not propagate labels
- remove split_conjunction, subsumed by split_goal

Encoding_instantiate keeps the type of the green part complexe.
Encoding_simple2 (bad name) replaces the complexe types by constants.

One day we can add a better comprehesion of (int,int) array for instance
 inside encoding_simple2 or inside the printers.