add event and pool structures

src/lib.ts

@@ -9,3 +9,5 @@ export { log_from, next, split_promise, wait } from "./lib/utils.ts";
 export { Chain } from "./lib/Chain.ts";
 export { Channel } from "./lib/Channel.ts";
 export { Range, range } from "./lib/Range.ts";
+export { Event } from "./lib/Event.ts";
+export { AsyncPool } from "./lib/AsyncPool.ts";