New `[locale='xx']...[/locale]` markup lets GUI text sections render
with a locale-specific font (e.g. CJK) while the rest of the caption
keeps the current game font.
guiObject.caption = "Hello [locale='ja']世界[/locale], how do you
[locale='zh']感覺[/locale]" This is ideal for language pickers and
similar UI where you want the language name shown in its own script.
This commit unlocks richer, self-explanatory international UI while
keeping the legacy text behaviour unchanged.