doc: adapt to the fact there's a real GltfImporter now.

I.e., with the intention to be implemented in the best way possible,
without relying on some 3rd party library with murky corner cases and
questionable tradeoffs.

doc/file-formats.dox

@@ -477,14 +477,14 @@ Together with @ref file-formats-image-importers "image importers" derived from
 <tr>
 <th rowspan="3">glTF<br/>(`*.gltf`, `*.glb`)</th>
 <td rowspan="3">`GltfImporter`</td>
-<td>@ref Trade::CgltfImporter "CgltfImporter"</td>
+<td>@relativeref{Trade,GltfImporter}</td>
-<td class="m-text-center m-success">@ref Trade-CgltfImporter-behavior "minor"</td>
+<td class="m-text-center m-success">@ref Trade-GltfImporter-behavior "minor"</td>
-<td class="m-text-center m-primary">bundled</td>
+<td class="m-text-center">@m_span{m-text m-dim} none @m_endspan </td>
-<td class="m-text-center m-success">MIT</td>
+<td class="m-text-center"></td>
 </tr>
 <tr>
-<td>@ref Trade::TinyGltfImporter "TinyGltfImporter"</td>
+<td>@ref Trade::TinyGltfImporter "TinyGltfImporter" @m_class{m-label m-danger} **deprecated**</td>
-<td class="m-text-center m-success">@ref Trade-TinyGltfImporter-behavior "minor"</td>
+<td class="m-text-center m-warning">@ref Trade-TinyGltfImporter-behavior "some"</td>
 <td class="m-text-center m-primary">bundled</td>
 <td class="m-text-center m-success">MIT</td>
 </tr>

src/Magnum/Trade/SceneData.h

@@ -1070,7 +1070,7 @@ However, since each @ref SceneField can be in a variety of types, you're
 expected to either check that the type is indeed what you expect using
 @ref fieldType(SceneField) const, or at least check with documentation of the
 corresponding importer. For example, because glTF files represent the scene
-in a textual form, @ref CgltfImporter will always parse the data into canonical
+in a textual form, @ref GltfImporter will always parse the data into canonical
 32-bit types. With that assumption, the above snippet that used
 @ref transformations3DAsArray() can be rewritten to a zero-copy form like this:
 

src/MagnumPlugins/AnySceneImporter/AnySceneImporter.h

@@ -70,8 +70,8 @@ tries to open the file with it. Supported formats:
 -   DirectX X (`*.x`), loaded with any plugin that provides `DirectXImporter`
 -   AutoCAD DXF (`*.dxf`), loaded with any plugin that provides `DxfImporter`
 -   Autodesk FBX (`*.fbx`), loaded with any plugin that provides `FbxImporter`
--   glTF (`*.gltf`, `*.glb`), loaded with any plugin that provides
+-   glTF (`*.gltf`, `*.glb`), loaded with @ref GltfImporter or any other plugin
-    `GltfImporter`
+    that provides it
 -   Industry Foundation Classes (IFC/Step) (`*.ifc`), loaded with any plugin
     that provides `IfcImporter`
 -   Irrlicht Mesh and Scene (`*.irrmesh`, `*.irr`), loaded with any plugin that