[boost] Serialization support for mersenne_twister

I know I've mentioned this before. I'd really like to see this tiny bit of code added to mersenne_twister: template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & x; ar & i; } This would make it very easy to use our new serialization library with mersenne_twister. It costs nothing if you don't use it. If you are really paranoid, it could be surrounded by an #ifdef.