rpatricia 0.06

* rely on Ruby GC for allocations/free
  no need to explicitly destroy objects anymore
* Ruby 1.9.2 C API compatibility
* allow creation of subclasses of Patricia class
* non-String objects may be stored as node-data
* Patricia::Node objects are returned when match succeeds
  It's no longer possible to call tree methods on node
  objects and cause segfaults.
* Patricia#show_nodes may be given a custom IO-like object
* sync docs with remove, match_best and match_exact behavior
* ArgumentError is raised for invalid addresses
  no more assertion failures for bad addresses
* Patricia#show_nodes and Patricia#num_nodes no longer
  segfaults on empty trees