giac CAS - first prototype

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@24165 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Redefine dialog changed to use DialogBox (#3091)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@24166 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
giac - missing files from last commit

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@24167 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Make spreadsheet view work again

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@24168 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e