[giac] fix problem sending Unicode.IMAGINARY to JS Giac

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25223 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Don't show browser's context menu in applets at all.

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25224 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e