LwjglContext: re-initialize renderer on context restart (lwjgl 2) (#1988)

* LwjglContext: initialize renderer on context restart (lwjgl 2).

* Reset GL objects in renderer when context restart.

jme3-lwjgl/src/main/java/com/jme3/system/lwjgl/LwjglContext.java

@@ -317,8 +317,8 @@ public abstract class LwjglContext implements JmeContext {
                     glfbo = (GLFbo) GLTracer.createDesktopGlTracer(glfbo, GLFbo.class);
                 }
                 renderer = new GLRenderer(gl, glext, glfbo);
-                renderer.initialize();
             }
+            renderer.initialize();
         } else {
             throw new UnsupportedOperationException("Unsupported renderer: " + settings.getRenderer());
         }

jme3-lwjgl/src/main/java/com/jme3/system/lwjgl/LwjglDisplay.java

@@ -150,6 +150,7 @@ public class LwjglDisplay extends LwjglAbstractDisplay {
         Display.setVSyncEnabled(settings.isVSync());
         
         if (created.get() && !pixelFormatChanged) {
+            renderer.resetGLObjects();
             Display.releaseContext();
             Display.makeCurrent();
             Display.update();