Added implicit conversions from Matrix<T> to Matrix<Complex> and from Vector<T> to Vector<Complex>, added matrix division

[PawelTroka]

Regarding issue #304, I don't know if it is good enough but this is as far as I got. It does not resolve issues related to Matrix<float> to Matrix<double> conversions thought. I had some discussion about it here: http://stackoverflow.com/questions/41795162/implicit-conversion-for-generic-class-restricted-only-to-some-types and it seems like an impossible task to do it in base type (Matrix<T>).

Regarding matrix division it's just one operator added, not a big deal.