Formula editor code for writer ([[sw]]).
Good overview from the original developer:
http://www.mail-archive.com/dev@sw.openoffice.org/msg00200.html
s://go.suokunlong.cn:88/cgit/lo/core/atom/filter/CppunitTest_filter_msfilter.mk?h=feature/skia' type='application/atom+xml'/>
