More instanceof fixes

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26197 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
[giac] Improve separate variables ode solving, fix for piecewise defined integration.

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@26198 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@26199 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e