OpenGL Render restored.

I tried to make it integrate more with regular render but couldn't
do it well, it still needs a 3D view to take the settings from, and
can't run in a separate thread due to OpenGL.

However, it is now rendering to an offscreen buffer which then gets
displayed in the image window. This requires FBO's to be available, so
a fallback creating a new window is still needed. Currently available
from the Render menu in the top header.

release/scripts/ui/space_info.py

@@ -206,6 +206,11 @@ class INFO_MT_render(bpy.types.Menu):
 
 		layout.itemS()
 
+		layout.itemO("screen.opengl_render", text="OpenGL Render Image")
+		layout.item_booleanO("screen.opengl_render", "animation", True, text="OpenGL Render Animation")
+
+		layout.itemS()
+
 		layout.itemO("screen.render_view_show")
 
 class INFO_MT_help(bpy.types.Menu):