Add imgui to Thyme to allow implementing custom debug functionality to game

[xezon]

Imgui allows to draw texts, menus and interactive UI elements on top of the game. This can be used to present debug information such as profilers or implement features that can be enabled and controlled on runtime. A limited set of features may even be presented to the end user, such as configuring max fps value, normally not available in the game.

Code: https://github.com/ocornut/imgui

For starters, ImDrawData needs to be punched in the DirectX render loop. This needs to happen before IDirect3DDevice8::Present is called and after all game vertices have been drawn.

imgui does provide code sample for DirectX 9. This can be adapted for DirectX 8. The same principles apply.

https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_dx9.h

[xezon]

Something for DX 8 here.

ocornut/imgui#5379

[xezon]

tomsons26:

We'd need game engine classes for that