message: feat(router): add back,forward,go
diff: @@ -104,6 +104,11 @@ export interface Router {
  push(to: RouteLocationRaw): Promise<NavigationFailure | void>
  replace(to: RouteLocationRaw): Promise<NavigationFailure | void>
  + // TODO: return a promise when https://github.com/vuejs/rfcs/pull/150 is
  + // merged
  + back(): void
  + forward(): void
  + go(distance: number): void
  beforeEach(guard: NavigationGuardWithThis<undefined>): () => void
  afterEach(guard: PostNavigationGuard): () => void
  @@ -605,10 +610,13 @@ export function createRouter({
  removeRoute,
  hasRoute,
  getRoutes,
  + resolve,
  push,
  replace,
  - resolve,
  + go: history.go,
  + back: () => history.go(-1),
  + forward: () => history.go(1),
  beforeEach: beforeGuards.add,
  afterEach: afterGuards.add,
  