Caper closure split updated to split strings separated by ' - ' outside of closures
[Usenet Parser] Fix for site matching
[Usenet Parser] Fix for file_name/size/yEnc matching
[Usenet Parser] Fixed test_town_style
Added 'target' attribute and cleaned up CaptureConstraint
CaptureGroup - split until method, changed when closures are split into fragments, check_constraints method now runs constraints that target the subject.

 - Split until method into until_closure and until_fragment
 - Closures are now split into fragments if we encounter a non-closure step
 - Updated check_constraints to only execute constraints for closure/fragment nodes.
[Usenet Parser] Updated to match more subjects, added another test_bare test subject.