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
```

4 files changed, 26 insertions, 3 deletions

diff --git a/source/blender/editors/interface/interface_eyedropper.c b/source/blender/editors/interface/interface_eyedropper.c
index 0a21c89e692..a50c0f5a4f4 100644
--- a/source/blender/editors/interface/interface_eyedropper.c
+++ b/source/blender/editors/interface/interface_eyedropper.c
@@ -597,7 +597,7 @@ static void datadropper_id_sample_pt(bContext *C, DataDropper *ddr, int mx, int
 				const int mval[2] = {
 				    mx - ar->winrct.xmin,
 				    my - ar->winrct.ymin};
-				Base *base;
+				BaseLegacy *base;
 
 				CTX_wm_area_set(C, sa);
 				CTX_wm_region_set(C, ar);
diff --git a/source/blender/editors/interface/interface_icons.c b/source/blender/editors/interface/interface_icons.c
index 0573e8d9c94..70bfd30c2d8 100644
--- a/source/blender/editors/interface/interface_icons.c
+++ b/source/blender/editors/interface/interface_icons.c
@@ -1385,6 +1385,14 @@ int UI_idcode_icon_get(const int idcode)
 	}
 }
 
+/**
+ * \param set_idx: A value from #rna_enum_color_sets_items.
+ */
+int UI_colorset_icon_get(const int set_idx)
+{
+	return (set_idx < 1) ? ICON_NONE : VICO_COLORSET_01_VEC - 1 + set_idx;
+}
+
 static void icon_draw_at_size(
         float x, float y, int icon_id, float aspect, float alpha,
         enum eIconSizes size, const bool nocreate)
diff --git a/source/blender/editors/interface/interface_widgets.c b/source/blender/editors/interface/interface_widgets.c
index b580d394dd0..84b022ca440 100644
--- a/source/blender/editors/interface/interface_widgets.c
+++ b/source/blender/editors/interface/interface_widgets.c
@@ -1576,7 +1576,10 @@ static void widget_draw_text_icon(uiFontStyle *fstyle, uiWidgetColors *wcol, uiB
 		}
 	}
 
-	if (but->editstr || (but->drawflag & UI_BUT_TEXT_LEFT)) {
+	if (but->drawflag & UI_BUT_TEXT_NO_MARGIN) {
+		/* skip */
+	}
+	else if (but->editstr || (but->drawflag & UI_BUT_TEXT_LEFT)) {
 		rect->xmin += (UI_TEXT_MARGIN_X * U.widget_unit) / but->block->aspect;
 	}
 	else if ((but->drawflag & UI_BUT_TEXT_RIGHT)) {
diff --git a/source/blender/editors/interface/resources.c b/source/blender/editors/interface/resources.c
index 76b8f348c9c..8bd671873be 100644
--- a/source/blender/editors/interface/resources.c
+++ b/source/blender/editors/interface/resources.c
@@ -167,6 +167,9 @@ const unsigned char *UI_ThemeGetColorPtr(bTheme *btheme, int spacetype, int colo
 				case SPACE_CLIP:
 					ts = &btheme->tclip;
 					break;
+				case SPACE_COLLECTIONS:
+					ts = &btheme->tcollections;
+					break;
 				default:
 					ts = &btheme->tv3d;
 					break;
@@ -1208,6 +1211,11 @@ void ui_theme_init_default(void)
 	rgba_char_args_set(btheme->tclip.strip_select, 0xff, 0x8c, 0x00, 0xff);
 	btheme->tclip.handle_vertex_size = 5;
 	ui_theme_space_init_handles_color(&btheme->tclip);
+
+	/* space collection manager */
+	btheme->tcollections = btheme->tv3d;
+	rgba_char_args_set_fl(btheme->tcollections.back,    0.42, 0.42, 0.42, 1.0);
+	rgba_char_args_set(btheme->tcollections.hilite, 255, 140, 25, 255);  /* selected files */
 }
 
 void ui_style_init_default(void)
@@ -2859,7 +2867,11 @@ void init_userdef_do_versions(void)
 	 * (keep this block even if it becomes empty).
 	 */
 	{
-		
+		for (bTheme *btheme = U.themes.first; btheme; btheme = btheme->next) {
+			btheme->tcollections = btheme->tv3d;
+			rgba_char_args_set_fl(btheme->tcollections.back,    0.42, 0.42, 0.42, 1.0);
+			rgba_char_args_set(btheme->tcollections.hilite, 255, 140, 25, 255);  /* selected files */
+		}
 	}
 
 	if (U.pixelsize == 0.0f)