Fix regionck to add constraints from type parameter bounds
Fix regionck to consider bounds on a proc when capturing variables
Fix regionck to account for the uniqueness requirements on ref mut reborrows
WIP: Additional test for 74895038102e0edbb08a9fbd4c40a966b9cd3c6f
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
wip: update comments
Implement skolemization