Change nrx_compare to be always present. In the base class it just compares for equality.
Add "map" operator.
Add "in" operator.
Update unit tests for new operators and split them into individual methods.
Enhance interpreter's scope feature by using blocks. Add traversal paradigm support. Rename 'in' operator to 'contains'.
Update to Xcode 5. Remove some warnings.
Add 'except' operator.
Make delegate node accept arbitrary delegates.