enumitem, since we already have a module for that, and I am a bit
worried about conflicts between enumerate.sty and enumitem.sty.
A side effect of this, however, is that we will load enumitem.sty
whenver we use case environments.
git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@40492 a592a061-630c-0410-9148-cb99ea01b6c8