[REQUEST] Support object rotating & flip

[finscn]

When the object & object's normal-mapping are rotating , the lighting will take some mistakes.

I hope it could support Support object rotating.

Like this :

http://fatidol.com/lights/

this demo used my lighting extension of PIXI v4.

https://github.com/finscn/pixi.js/tree/v4-plus/src/ext-plugins/lighting

I think mine is better than pixi-lights.

Support more features and with better performance.

[finscn]

I want to create PR.

But I found that , the arguments of my lighting-extension are different from pixi-lights.

in other words , uses have to face the problem of incompatibility.

[ivanpopelyshev]

Somehow connected to https://github.com/pixijs/pixi.js/issues

[pietrovismara]

@finscn @ivanpopelyshev Any tip on how could this be done? I would be happy to pay to get this and possibly other improvements working.