[giac] fix for #3791
make simplify(diff(int(1/(x^n+1)))) work for bigger values of n (5, 7, ...)
fix diff(exp(x)) returning 0
add some 2nd order ode solving
add degree overflow check for polynomials
protect concurrent access to syms() by a mutex

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29822 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@29823 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e