Fix regionck to consider bounds on a proc when capturing variables
Fix regionck to account for the uniqueness requirements on ref mut reborrows
Fix kindck to consider inherited bounds
Refactor and cleanup inference code: s/get_ref()/fields/, use try! macro rather than if_ok!
Introduce snapshot_vec abstraction
Introduce new inference scheme: variables are now instantiated with at most one type, and region variables are introduced as needed
Implement skolemization