ImGui improvement

This is a checklist to trace current work.

Version bump work

• Fixup the debug console input box. Multiline and History can't supported at the same time in origin imgui.

Improtant improvement

• IMGUI version upgrade
• Multiview support
• Docking support
• IME fix.
• More convenient font setthings pannel
• Windows doesn't show in full screen mode, if part of them're moved outside the game window.
• Check the lua functions like WorldToImGui because the multiview's window position is relative to monitor, instead of game window.
• ImGui.WorldToImGui not work properly in full screen mode.
• Make ImGui's position relative to game main window.
• Add more error handle in muiltiview impl things.
• fix impl of ImGui.GetMousePosition()

Document update

• update document for ImGui.WorldToImGui, remove bug description.
• document ImGui.GetGameWindowRect()
• fix document about ImGui.GetMousePosition()
• document ImGuiWindowFlags.NoDocking

Font related improvement

Thanks to the dynamic font support from imgui we could do better with fonts.

• Render emoji properly
• Pixelated font rendering. almost did nothing. unifont is already a pixel font.
• Adjust freetype's font hinting for pixel font.
• Support system font selection
• Add better alternative fonts? e.g. use native system fonts or add fonts that some non-english people prefer

Docking feature

• Consider disable docking feature if we merge to main branch. It's still under development.
• expose NoDocking window flag for mods.

Know issue

Not much important, should be fine without fix.

• Can't input emoji with IME in the window created by imgui
• Game crash with zero window size when open console.
• window position shift before/after toggle fullscreen.
• Ctrl+Mousewheel doesn't work property in some texts. Because the FontWindowScale not work properly. See the obsolute message from imgui.
• Fix or remove the imgui's font setthings. Basically it's a developer panel I think. The font settings actually doesn't work now.
• Docking tab size not correct with ctrl+mousewheel scale.
• Docking window can't move outside game window, when game in fullscreen or linux environment.
• Can't render fonts in multi-viewport window + linux, most likely wglShareLists not works. tmp solution: multi-viewport is disabled in linux by default.

Test

• Clipboard support.
• The imgui test mod.
• Steam Deck compatability.

Idea that doesn't work

support subpixel font rendering
Nope. FT_PIXEL_MODE_LCD can't render colored emoji.

The issue lists several unchecked ImGui tasks, including system font selection, alternative fonts, zero-size console crashes, fullscreen position shifts, and font settings. No implementation files or tests are named, so first choose one item and trace its existing ImGui integration; done means that item is implemented and its behavior is verified without regressing the completed checklist items.