feat(scope): new and improved scope implementation

- Speed improvements (about 4x on flush phase)
- Memory improvements (uses no function closures)
- Break $eval into $apply, $dispatch, $flush
- Introduced $watch and $observe

Breaks angular.equals() use === instead of ==
Breaks angular.scope() does not take parent as first argument
Breaks scope.$watch() takes scope as first argument
Breaks scope.$set(), scope.$get are removed
Breaks scope.$config is removed
Breaks $route.onChange callback has not "this" bounded