DemoPolygonPhysics crashes when run standalone

[RandomReaper]

but it runs in the DemoSelector

Exception in thread "LWJGL Application" com.badlogic.gdx.utils.GdxRuntimeException: java.lang.UnsatisfiedLinkError: com.badlogic.gdx.physics.box2d.PolygonShape.newPolygonShape()J
at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:127)
Caused by: java.lang.UnsatisfiedLinkError: com.badlogic.gdx.physics.box2d.PolygonShape.newPolygonShape()J
at com.badlogic.gdx.physics.box2d.PolygonShape.newPolygonShape(Native Method)
at com.badlogic.gdx.physics.box2d.PolygonShape.(PolygonShape.java:29)
at ch.hevs.gdx2d.lib.physics.AbstractPhysicsObject.createPolygonObject(AbstractPhysicsObject.java:98)
at ch.hevs.gdx2d.lib.physics.AbstractPhysicsObject.(AbstractPhysicsObject.java:57)
at ch.hevs.gdx2d.components.physics.primitives.PhysicsPolygon.(PhysicsPolygon.java:43)
at ch.hevs.gdx2d.demos.physics.DemoPolygonPhysics.onInit(DemoPolygonPhysics.java:54)
at ch.hevs.gdx2d.desktop.Game2D.create(Game2D.java:174)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:143)
at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:120)

[RandomReaper]

It seems the physics world is not initialized. PhysicsWorld.getInstance() fix it...

[metc]

Good point @RandomReaper
I tested with the demo selector gdx2d-demoDesktop-1.2.1.jar and it doesn't work either. If no other physics demo are launched before the DemoPolygonPhysics, the bug also appears in the demo selector.

I am not sure if we should really initialize the physics world for all applications because not all the demo use the `PhysicsWorld``...

[RandomReaper]

The demo works if another demo using physics and calling PhysicsWorld.getInstance() have been run before...

I think creating an unused variable using PhysicsWorld.getInstance() in the constructor of the PortableApplication is counter-intuitive and initializing the physics world is not so expensive.