Method reserve

KBotExt/imgui/imgui.h:2311–2311

	bool                empty() const { return Buf.Size <= 1; }
	void                clear() { Buf.clear(); }
	void                reserve(int capacity) { Buf.reserve(capacity); }
	const char* c_str() const { return Buf.Data ? Buf.Data : EmptyString; }
	IMGUI_API void      append(const char* str, const char* str_end = NULL);
	IMGUI_API void      appendf(const char* fmt, ...) IM_FMTARGS(2);