Mersenne Twister random number generator

The code is based on the official MT19937 implementation
It is fully rewritten:

http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html

todo: fixing copyright information

/*!

\page ugraphs Undirected graph structures

The primary data structures of LEMON are the graph classes.

Under construction.

*/