Minimal timeout support for Giac. The "non-exception" DLL causes a TimeoutException when Giac returns properly (in many cases), and the connection will be lost with Giac. The "exception" DLL gives no exception, but simply returns with undefined. This looks somewhat better.

TODOs:

* Test if the exception DLL can return with TimeoutException (for compatibility).
* Restart Giac after the exception to make it possible to use Giac again in the current GeoGebra session.

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29559 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e