Add a way to add unlimited number of FB to the shader
10 custom FBs is someting not enough.
A good way could be to add a multiAttribute to the deex_buffer_writter.
The prob if we remove the 10 custom FBs to replace them by a multiIndice attr is that this will break compatibility with old system.
What I purpose is to add a multiIndice attr, keep the ten custom FBs in the code but remove them from the AE "exposure" (the mi file).
The multiIndice way could eb done following this method: