implement a graphical demo launcher in SWT

[chirontt]

A graphical SWT application showing the demo classes in a tree structure, and to launch the demos in separate processes.

To build:

mvnw package -Dclass=DemoLauncher

Then run the launcher app:

java -jar target/lwjgl3-demos.jar

Or to launch a specific demo directly, e.g. VoxelGameGL:

java -jar target/lwjgl3-demos.jar game.VoxelGameGL

(the org.lwjgl.demo. package prefix is automatically prepended to the above demo class.)

Or to launch a specific demo with arguments, e.g. Bump:

java -jar target/lwjgl3-demos.jar bgfx.Bump --gl --intel