Render Layers and Collections (merge from render-layers)

Design Documents
----------------

* https://wiki.blender.org/index.php/Dev:2.8/Source/Layers

* https://wiki.blender.org/index.php/Dev:2.8/Source/DataDesignRevised

User Commit Log
---------------

* New Layer and Collection system to replace render layers and viewport layers.

* A layer is a set of collections of objects (and their drawing options) required for specific tasks.

* A collection is a set of objects, equivalent of the old layers in Blender. A collection can be shared across multiple layers.

* All Scenes have a master collection that all other collections are children of.

* New collection "context" tab (in Properties Editor)

* New temporary viewport "collections" panel to control per-collection
visibility

Missing User Features
---------------------

* Collection "Filter"
  Option to add objects based on their names

* Collection Manager operators
  The existing buttons  are placeholders

* Collection Manager drawing
  The editor main region is empty

* Collection Override

* Per-Collection engine settings
  This will come as a separate commit, as part of the clay-engine branch

Dev Commit Log
--------------

* New DNA file (DNA_layer_types.h) with the new structs
  We are replacing Base by a new extended Base while keeping it backward
  compatible with some legacy settings (i.e., lay, flag_legacy).

  Renamed all Base to BaseLegacy to make it clear the areas of code that
  still need to be converted

  Note: manual changes were required on - deg_builder_nodes.h, rna_object.c, KX_Light.cpp

* Unittesting for main syncronization requirements
  - read, write, add/copy/remove objects, copy scene, collection
  link/unlinking, context)

* New Editor: Collection Manager
  Based on patch by Julian Eisel
  This is extracted from the layer-manager branch. With the following changes:

    - Renamed references of layer manager to collections manager

    - I doesn't include the editors/space_collections/ draw and util files

    - The drawing code itself will be implemented separately by Julian

* Base / Object:
  A little note about them. Original Blender code would try to keep them
  in sync through the code, juggling flags back and forth. This will now
  be handled by Depsgraph, keeping Object and Bases more separated
  throughout the non-rendering code.

  Scene.base is being cleared in doversion, and the old viewport drawing
  code was poorly converted to use the new bases while the new viewport
  code doesn't get merged and replace the old one.

Python API Changes
------------------

```
- scene.layers
+ # no longer exists

- scene.objects
+ scene.scene_layers.active.objects

- scene.objects.active
+ scene.render_layers.active.objects.active

- bpy.context.scene.objects.link()
+ bpy.context.scene_collection.objects.link()

- bpy_extras.object_utils.object_data_add(context, obdata, operator=None, use_active_layer=True, name=None)
+ bpy_extras.object_utils.object_data_add(context, obdata, operator=None, name=None)

- bpy.context.object.select
+ bpy.context.object.select = True
+ bpy.context.object.select = False
+ bpy.context.object.select_get()
+ bpy.context.object.select_set(action='SELECT')
+ bpy.context.object.select_set(action='DESELECT')

-AddObjectHelper.layers
+ # no longer exists
```

1 files changed, 8 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_context.h b/source/blender/blenkernel/BKE_context.h
index 4da6a61cbfa..23f9ff28f8b 100644
--- a/source/blender/blenkernel/BKE_context.h
+++ b/source/blender/blenkernel/BKE_context.h
@@ -40,12 +40,16 @@ extern "C" {
 struct ARegion;
 struct bScreen;
 struct CacheFile;
+struct LayerCollection;
 struct ListBase;
 struct Main;
 struct Object;
+struct Base;
 struct PointerRNA;
 struct ReportList;
 struct Scene;
+struct SceneCollection;
+struct SceneLayer;
 struct ScrArea;
 struct SpaceLink;
 struct View3D;
@@ -166,6 +170,7 @@ struct SpaceAction *CTX_wm_space_action(const bContext *C);
 struct SpaceInfo *CTX_wm_space_info(const bContext *C);
 struct SpaceUserPref *CTX_wm_space_userpref(const bContext *C);
 struct SpaceClip *CTX_wm_space_clip(const bContext *C);
+struct SpaceCollections *CTX_wm_space_collections(const bContext *C);
 
 void CTX_wm_manager_set(bContext *C, struct wmWindowManager *wm);
 void CTX_wm_window_set(bContext *C, struct wmWindow *win);
@@ -239,6 +244,9 @@ int ctx_data_list_count(const bContext *C, int (*func)(const bContext *, ListBas
 
 struct Main *CTX_data_main(const bContext *C);
 struct Scene *CTX_data_scene(const bContext *C);
+struct LayerCollection *CTX_data_layer_collection(const bContext *C);
+struct SceneCollection *CTX_data_scene_collection(const bContext *C);
+struct SceneLayer *CTX_data_scene_layer(const bContext *C);
 struct ToolSettings *CTX_data_tool_settings(const bContext *C);
 
 const char *CTX_data_mode_string(const bContext *C);