maintenance: imgui update to v 1.73

ref/imgui/examples/imgui_impl_dx10.h

@@ -1,13 +1,16 @@
-// ImGui Renderer for: DirectX10
+// dear imgui: Renderer for DirectX10
 // This needs to be used along with a Platform Binding (e.g. Win32)
 
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'ID3D10ShaderResourceView*' as ImTextureID. Read the FAQ about ImTextureID in imgui.cpp.
+//  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bits indices.
 
 // You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
 // If you are new to dear imgui, read examples/README.txt and read the documentation at the top of imgui.cpp.
 // https://github.com/ocornut/imgui
 
+#pragma once
+
 struct ID3D10Device;
 
 IMGUI_IMPL_API bool     ImGui_ImplDX10_Init(ID3D10Device* device);