BIG FAT COMMIT REGARDING COERCIONS:

BIG FAT COMMIT REGARDING COERCIONS:
- multiple coercions from the same type
- coercions to funclass
- fixed cicPp for letin and pi
- improved coercions ma with a minimal test for funclass
- cheanged XML and Ast to support `Coercion ARITY label
- added syntax:
  coercion URI ARITY
  recordfield :ARITY> type
- added topological sorting module (funcotr) in extlib
- abstracted graphviz to allow non strict and tred graphs
- tentative (not yet properly done) of hiding coercions in content
- fixed a problem in metadata contraints iof there are no constraints
- renamed/moved/commented some functions (eat_prod related) in the refiner
- crossed fingers