Bold button for CAS Stylebar - half way (#3530)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29264 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Bold button works on cas style bar. (Stylebar update needed yet.) (#3530)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29265 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
CAS stylebar updates after clicking on its button. (#3530)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29266 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Italic button added for CAS style bar (#3530)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29267 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e