New release MathGL v.2.5

[Alexey Balakin]

I glad to announce new release of MathGL. There are big improve in formula evaluation (user-defined function, summation and product, new functions for data interpolation), new plot kind dcont and lines, set of functions for random distributions, new data handling functions (like, keep), extend ode to solve PDE/cascade/etc, add mask for most of plotting functions and bugfixes, which denoted here.