add legacy support of checkbox, add documents for cookie/lgres/request

lib/utility/lgres.d.ts

@@ -3,7 +3,11 @@ interface LgresOptions {
     callback?: (result: any) => void
 }
 
-export function init(dom?: HTMLElement, options?: LgresOptions): Promise<any>
+interface LanguageResource {
+    r(key: string, defaultValue?: any): any
+}
+
+export function init(dom?: HTMLElement, options?: LgresOptions): Promise<LanguageResource>
 export function r(key: string, defaultValue?: any): any
 export const lang: {
     get current(): string,