Include the "not-well-formed" error condition

Tinder should include the "not-well-formed" error condition that replaces the older "xml-not-well-formed" condition.

Interoperability Note from RFC6120, paragraph 4.9.3.13. not-well-formed:

Interoperability Note: In RFC 3920, the name of this error
condition was "xml-not-well-formed" instead of "not-well-formed".
The name was changed because the element name <xml-not-well-
formed/> violates the constraint from Section 3 of [XML] that
"names beginning with a match to (('X'|'x')('M'|'m')('L'|'l')) are
reserved for standardization in this or future versions of this
specification".