integration for GLUT about pyimgui

[swistakm]

I remember that i wanted to provide integration with GLUT because it has very simple API and is always available with OpenGL.

Still I don't remember why I didn't do this because it should be pretty straightforward to do with the base classes for OpenGL integration, both fixed and programmable pipeline. It had to do something with the way GLUT exposes user inputs (mouse, keyboard, etc.). If I recall correctly, it provides only a way to attach callbacks to specific input events but does not provide functions to query mouse state (like getMousePosition()). Probably I wasn't ready at that time to make opinionated decisions on how to handle these inputs so I simply left it for future.

Generally it might be nice to have built-in GLUT integration because it allows to make a demo application with probably the least amount of dependencies (only OpenGL) but it think that currently this is a feature with the lowest priority possible.