Make sure AV does not use Italic for LaTeX

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25251 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Allow redefining ab(x)=1/x in AV [needs backport]

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25252 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e