GLRenderer: support limited NPOT on iOS

See this: 
https://www.khronos.org/registry/gles/extensions/APPLE/APPLE_texture_2D_limited_npot.txt

Note that NPOT is still not available on cubemaps or 3D textures, however this is fairly uncommon.

jme3-core/src/main/java/com/jme3/renderer/opengl/GLRenderer.java

@@ -343,6 +343,7 @@ public class GLRenderer implements Renderer {
 
         if (hasExtension("GL_ARB_texture_non_power_of_two") || 
             hasExtension("GL_OES_texture_npot") ||
+            hasExtension("GL_APPLE_texture_2D_limited_npot") ||
             caps.contains(Caps.OpenGL30)) {
             caps.add(Caps.NonPowerOfTwoTextures);
         } else {