[giac] Fix for #4604
Fix for integrals with surd.
Changed derivative of abs(x) from sign(x) to abs(x)/x (returns now undef at x=0)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36770 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Changing giac.js to the latest version in web/kickstart.xml

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36771 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e