Removed noisy debug output.
Corrected throw statement so we don't throw 'undefined'.
Corrected error message for NotIterable error thrown by ForNode.
Added the InvalidValue and NotNumeric error classes.
Added the custom 'range' filter.
Corrected for loop iteration so the counter[0], revcounter[0], first, and last variables are set correctly.
Corrected FilterExpression.error() to throw more useful error messages.
Updated regex to correctly detect 'failed' conditions that aren't followed by 'Expected:' and 'Actual:'.
Corrected FilterExpression.error() even more; now, you can pass formatting arguments, and the error messages are much more readable.
Corrected tags to actually allow filter expressions in appropriate tag parameters, instead of only allowing variables or literals. Also, factored out common functions used with Array.map() calls.
Updated tests to work with the latest changes.