Blender Git Loki

Fix unfreed memory after cleaning render layers

The freestyle data was never freed when removing a renderlayer.

```
blender -b --factory-startup --debug-memory --python-expr "import bpy;bpy.ops.scene.render_layer_add();bpy.context.scene.render.layers.active_index=0;bpy.ops.scene.render_layer_remove()"
```