Cross Platform GUI for CCExtractor

Cross Platform GUI for CCExtractor using Nuklear library. Since, Nuklear library doesn't incur additional dependency and draws its own widgets, the GUI would look exactly the same on all major platforms. The simplistic UI design aims to improve UX even for the user using CCExtractor for the first time. Nuklear mostly uses OpenGL (GLFW and GLEW) as render backend. Since, use of these libraries are common across GUI development in Immediate Mode Graphical User Interface Development, the project aims to lower down the maintenance efforts too.