Due to multi pass approach to lighting in GLES2, in some situations the rendered result can look different if lights are presented in a different order.
The order (aside from directional lights) seems to be simply copied from the culling routine (octree or bvh) which is essentially arbitrary. While octree is usually consistent with order, bvh uses a trickle optimize which may result in lights occurring in different order from frame to frame.
This PR adds an extra layer of sorting on GLES2 lights in order to get some kind of order consistency.
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