Multiple Backend Support

[duysqubix]

OpenGL is the main graphics library supporting Pixel.

We want Pixel to support multiple graphics library in the future. From Vulcan, SDL, DirectX, etc...

Let this issue stand as a open action item until we can officially close it.

• Parent
  • Issue:(SubTask - Refactor Pixel Project #63), PR:(refactoring project #64)
  • Issue:(SubTask - Define a standard set of inputs in pixel core #66)
  • Issue:(SubTask - Pull Joystick code out of opengl backend #68)
  • Issue:(SubTask - We'll need to define a pixel.Action (Press, Release, Repeat) to move joystick out of opengl #69)
  • Issue:(SubTask - Split shared parts of Window from opengl backend #70)