<ptr> in <desc> gets dropped in rng

[npcole]

While investigating issue #399, it became clear that the processing of <ptr> was also incorrect.

[sydb]

When we fixed #399, we only did <code>, but also found <ptr> is problematic. The fix for <ptr> is not as easy, though. My personal thought (at the moment) is rather than try to fix this particular little problem, the entire thing (processing of <gloss> and <desc> into RELAX NG annotations) should be ripped out and re-written as processing in a special-purpose mode.