Additional matrix and vector functions

Some additional functions to the ``Numerical Recipes in C`` library are present like:

• matrix multiplication (matmult)
• matrix vector multiplication (matvecmult)
• vector vector multiplication (vecinmult)
• matrix transpose (mattransp)
• matrix copy (matcopy)
• matrix inverse (matinv and matinvd)

Furthermore, two functions are implemented to print out matrices and vectors (fprintf_vector and fprintf_matrix) in a formatted way. Full details can be found in the reference part of the manual.