Remove 4 repos from Game Development section. (#1003)

README.md

@@ -406,7 +406,6 @@ Please take a quick gander at the [contribution guidelines](https://github.com/a
 * [Ebiten](https://github.com/hajimehoshi/ebiten) - A simple SNES-like 2D game library in Go
 * [engo](https://github.com/EngoEngine/engo) - Engo is an open-source 2D game engine written in Go. It follows the Entity-Component-System paradigm.
 * [GarageEngine](https://github.com/vova616/GarageEngine) - 2d game engine written in Go working on OpenGL.
-* [glm](https://github.com/luxengine/glm) - A performance oriented vector, matrix, geometry library.
 * [glop](https://github.com/runningwild/glop) - Glop (Game Library Of Power) is a fairly simple cross-platform game library.
 * [go-astar](https://github.com/beefsack/go-astar) - Go implementation of the A\* path finding algorithm
 * [go-collada](https://github.com/GlenKelley/go-collada) - Go package for working with the Collada file format.
@@ -414,10 +413,7 @@ Please take a quick gander at the [contribution guidelines](https://github.com/a
 * [go3d](https://github.com/ungerik/go3d) - A performance oriented 2D/3D math package for Go
 * [gonet](https://github.com/xtaci/gonet) - A game server skeleton implemented with golang
 * [Leaf](https://github.com/name5566/leaf) - A lightweight game server framework
-* [lux](https://github.com/luxengine/lux) - A 3D physically based rendering engine.
-* [math](https://github.com/luxengine/math) - A float32 native version of standard library math.
 * [termloop](https://github.com/JoelOtter/termloop) - Terminal-based game engine for Go, built on top of Termbox
-* [tornago](https://github.com/luxengine/tornago) - A 3D rigid body physics engine in pure Go.
 
 
 ## Generation & Generics