Cull the scenery models drawn on their own on the GPU with the instances

docs/opengl46-renderer.md

@@ -281,6 +281,7 @@ cab and other views go as before.
 | `gfx.gpucull.shadows.headlights yes/no` | `yes` | with `gfx.gpucull yes` or `compare`: the models of the shadow maps of headlights too (each map tested against the beam it is drawn with, to its reach, the distances from the real camera, as before) |
 | `gfx.gpucull.shadows.lamps yes/no` | `yes` | with `gfx.gpucull yes` or `compare`: the models of the scenery part of the shadow maps of scenery lamps too (each map tested against the reach of its lamp, as before); the part with the vehicles has no models of the scenery |
 | `gfx.gpucull.sleepers yes/no` | `yes` | with `gfx.gpucull yes` or `compare`: the sleepers of the tracks (`sleepermodel`) of the main view too, each one tested against the view and given its level of detail by its distance, as before (the tracks within `sleeperdistance` are chosen as before); they also take the occlusion test, the depth prepass and the two phases of the models |
+| `gfx.gpucull.models yes/no` | `yes` | with `gfx.gpucull yes` or `compare`: the models drawn on their own too (scenery models with lights, animations, or skins and animations given by events, which the instanced draws leave out), in every pass the instances are culled in: each such model is tested on its own like the others (visibility, the view, its range, the draw range, its size on the screen) and given the level of detail its distance picks from the `mindistance`/`maxdistance` of its submodels; the processor animates and prepares the model only to record what it draws. Models with billboards turned to the camera stay on the processor, and so do vehicles |
 | `gfx.depthprepass.scene yes/no` | `no` | the depth of the whole opaque scene of the main view (terrain, tracks, buildings, models, vehicles, the cab) is drawn before its colour, see below |
 | `gfx.depthprepass.replay yes/no` | `yes` | the scene is gone through once for its depth and its colour: what the colour pass draws is recorded and both are drawn from the record, see below. `no`: twice, as before |
 
@@ -413,7 +414,9 @@ editor goes through the first `dynamiclights` headlights, the reflections throug
   slot of the map), and for the scenery of the maps of lamps, `gpu cull lamp shadows, scenery 1:` and `2:` (the first and
   the second drawn in a frame), each with the numbers of its last drawing and the timings `instance cull headlight shadows 1:`
   … and `instance cull lamp shadows, scenery 1:` …. With `gfx.gpucull.sleepers` the row
-  `gpu cull:` is followed by how many sleepers of how many tracks were queued (they are counted among the models).
+  `gpu cull:` is followed by how many sleepers of how many tracks were queued (they are counted among the models). With
+  `gfx.gpucull.models` each `gpu cull` row is followed by how many models drawn on their own were queued (also counted
+  among the models).
 - With `gfx.depthprepass.scene yes` Shift+F12 shows the `scene depth:` row (draws of the depth pass and its processor time)
   and the timing `scene depth:` (its GPU time). With `gfx.depthprepass.replay yes` the row tells how many of the recorded
   parts (of models, of the scenery; neighbouring tracks count one by one) had their depth drawn, in how many calls, how many