* lisp/org-pcomplete.el (pcomplete/org-mode/prop): Add
`ignore-malformed' argument in call to `org-buffer-property-keys'
* lisp/org.el (org-buffer-property-keys): Add support for new argument
`ignore-malformed'.
* testing/lisp/test-org-pcomplete.el: Add new file for testing
`pcomplete' integration.
* testing/lisp/test-org.el (test-org/buffer-property-keys): Test
behaviour of `org-buffer-property-keys' with new `ignore-malformed'
argument.
When property name completion is being performed, it means that we are
inside malformed property drawer that will become valid only after
successful completion. In this case in makes no sense to perform
interactive drawer repair.
