XS.only_more() becomes XS.options_forward(), change behavior and update tests:
- Rename only_more into options_forward
- options_forward():
  - only set _t.more to 'true' if source transaction more is truly
  - do not add _t.more if not truly
  - only add _t Object if there is at least one property in output transaction
  - Modify tests to test transaction object
  - Add ToDos
  - Update documentation