- Add coverage for dict collections, and fixes for dict support.

- Add coverage for dict collections, and fixes for dict support.
- Default dict appender name now 'set' to be consistent with duck_typing,
  prefer to remove default appender/remover methods from dict altogether.
- Add coverage for MappedCollection and OrderedDict derived dict collections
- Add coverage for raw object collections
- Fix OrderedDict pop() etc., [ticket:585]
- Update orderinglist unit test and remove 'broken until #213' assertion