worf.el (worf-property): improve
worf.el (worf-mark): add and bind to "m"
worf.el ("new"): add and bind to "n"

* worf.el (worf-new-right): New function.
  (worf-new-down): New function.
worf.el (worf-property): update
worf.el (worf-back-to-heading): add
worf.el (worf-delete-backward-char): add and bind to "DEL"

* worf.el (worf-delete-backward-char): Will reveal a hidden heading.