Differential Solvers library

DiSol is a C++ library built on top of Drayn to solve systems of differential equations. The design resembles that of Boost's odeint library, but with added constrains on the state-type and memory allocation, and using a pub-sub pattern to provide hooks during integration. There are several solvers currently implemented; explicit and implicit, with fixed or adaptive time-steps. Suggestions for improvement or future developments are most welcome (please open an issue).