Animation Channel Filtering Refactor - Part 1

* Removed list-expanders for Materials, Textures, and Particles. So
instead of:
  Object
     Materials
        Material 1
             ... material 1 anim data ...
  we now have
  Object
     Material 1
         ... material 1 anim data ...
 This makes it faster+easier to get to these items. If you don't want
to see all of these, you can still use the data-block filters from the
header to hide these.

* Internal cleanup - removed "owner" and "ownertype" settings from
bAnimListElem. The purpose of these was muddled, and more of a hassle
to maintain than doing anything useful - it was only really used for
the stuff above.

* Removed need for "sa->spacedata.first" casts all over the show for
animation editor tools which needed access to editor data. This can
now be retrieved directly.

source/blender/editors/space_action/action_draw.c

@@ -248,8 +248,6 @@ void draw_channel_strips(bAnimContext *ac, SpaceAction *saction, ARegion *ar)
 							break;
 						
 						case ANIMTYPE_FILLACTD:
-						case ANIMTYPE_FILLMATD:
-						case ANIMTYPE_FILLPARTD:
 						case ANIMTYPE_DSSKEY:
 						case ANIMTYPE_DSWOR:
 						{