IT++ full changelog

* Added SISO class implementing several algorithms used in turbo decoders/
receivers
* Added EXIT class for EXIT chart computation of turbo receivers
* Added STC class for the generation of Space Time block codes used in MIMO
systems with turbo receivers
* Added support for testing IT++ library in Visual Studio 2008. Current approach
relies on fc (file compare) utility which seems to be available only in Visual
Studio 2008.
* Added rank() function, which calculates the rank of a matrix by counting
the number of non-zero singular values. SVD function from LAPACK is thus
required by this function.
* Added implementation of Gamma(alpha, beta) random number generator. The
implementation of the Gamma_RNG::sample() function was taken from the R
statistical language.
* Added qr() overloaded function that does not compute Q. For some tasks
(triangularization) the Q matrix is not really needed.