Pass to warn about usage of tickets

This is a self pass (in self_ast_typed) that tries to find multiple usages of non-duplicable values (because of tickets).

Note: as the comments below reflect, currently it does not handle the situation in which a ticket variable is closed in a function.

It also does a small rework on the output of warnings, as otherwise, if not using --disable-michelson-typechecking, it would just display the typing error and not the warning information telling the user that a non-duplicable value was used multiple times.

closes #1088 (closed)