Customizable render layers for more entities

[321freddy]

Currently you can only change the render_layer property for very few entities like smoke and simple-entity.
It would be nice if more entity types would support this.

Specifically I want to create elevated train tracks and for this it would be necessary to either change the render layer of rails or of locomotives/cargo wagons.
Currently I'm making the tracks invisible and spawn additional visual entities of type "simple-entity" ontop (which support custom render layers) because the tracks themself seem to be always drawn underneath of everything. But this creates new clipping issues with the locomotive...

[Mooncat]

So you have made this request. Please allow me to add a few:
- render layer for inserter base
- render layer for the light indicator of fluid turrets.

I hope render layers can be changed per sprite rather than per entity, but I know it is difficult to do.

[Arcitos]

Please let me extend the previously mentioned list of entities by constant combinators.

Currently, setting the render_layer to "floor" will be ignored by the game for any kind of cc-based entities (like pressure plates or signs). This results in ugly clipping effects, as soon as vehicles drive across those entities.

Is it posible to remove the hardcoded render_layer for constant combinators, like it has been done recently for vehicles?