Add better frame rate handling than busy-waiting for an assumed 60 FPS

[twaritwaikar]

Master HEAD: v2

This:

Rubeus/RubeusCore/Source/Architecture/engine.cpp

Line 125 in 5f791c5

if(glfwGetTime() - lastFrameEndTime >= 1.0f / 60.0f)

...is assuming 60 FPS as the base FPS and attempts to busy-wait if the game exceeds 60 FPS.

Add a way to lower this limit in case the frame rate is set to something lower, or the FPS is not really being met to 60 FPS