Blender Git Loki

Fixed an issue regarding render layers. Now the Freestyle renderer builds a view map based on selected object layers in a render layer, instead of the global selection of object layers. This allows, for example, to have two render layers, one for rendering solid faces in all object layers, and the other for rendering outlines of objects in selected object layers by Freestyle. At the moment, the number of Freestyle-enabled render layers is restricted to one -- a better fix is in the future work.