UI: preset popover buttons in panel headers.

Moves the preset into a menu for the panel header, so it can be changed
without opening the panel and takes up less space. Two remaining issues:

* For long lists the add new preset button can be scrolled off screen.
* We should support showing the name of the chosen preset in the panel
  header, but the current preset system does not support detecting which
  preset is used.

Differential Revision: https://developer.blender.org/D3366

release/scripts/startup/bl_ui/properties_data_lamp.py

@@ -22,14 +22,6 @@ from bpy.types import Menu, Panel
 from rna_prop_ui import PropertyPanel
 
 
-class LAMP_MT_sunsky_presets(Menu):
-    bl_label = "Sun & Sky Presets"
-    preset_subdir = "sunsky"
-    preset_operator = "script.execute_preset"
-    COMPAT_ENGINES = {'BLENDER_RENDER', 'BLENDER_EEVEE'}
-    draw = Menu.draw_preset
-
-
 class DataButtonsPanel:
     bl_space_type = 'PROPERTIES'
     bl_region_type = 'WINDOW'
@@ -352,7 +344,6 @@ class DATA_PT_custom_props_lamp(DataButtonsPanel, PropertyPanel, Panel):
 
 
 classes = (
-    LAMP_MT_sunsky_presets,
     DATA_PT_context_lamp,
     DATA_PT_preview,
     DATA_PT_lamp,