This fixes several long "unusual contents found" warnings that
were being written from LyX's math parser and improves the
typesetting.
Thank you to Enrico for the fix. See here for his explanation:
http://www.mail-archive.com/lyx-devel@lists.lyx.org/msg180763.html
There are still two such warnings that might indeed be serious,
one each in fr/xypic.lyx and ja/xypic.lyx. I get an assertion
from cursor movement in those insets with instant preview enabled
(on both current trunk and branch).
