patch for expand.

Hello everybody, I found out that calling the expand() method on an expression like (d*sqrt(a+b)+a*sqrt(c+d))*(b*sqrt(a+b)+a*sqrt(c+d)) results in sqrt(b+a)*b*sqrt(d+c)*a+(d+c)*a^2+d*(b+a)*b+d*sqrt(b+a)*sqrt(d+c)*a This result could be further expanded. A patch that is supposed to make this happen is attached. Best regards, Chris