Managed to parse factorial.simple
   - made the parser return a TermCons with 0 children for the list terminator
   - fixed CollectPrioritiesVisitor not being called properly
   - added data structures in Context for associativity information
   - updated the PriorityFilter to take into consideration associtivity
Still to do:
   - fix some examples
   - fix instantiation for constants to reference the production
   - fix the JUnit regression tests.