Switch from Knex to TypeORM. Update Knub.

src/data/db.ts

@@ -0,0 +1,23 @@
+import { SimpleError } from "../SimpleError";
+import { Connection, createConnection } from "typeorm";
+
+let connectionPromise: Promise<Connection>;
+
+export let connection: Connection;
+
+export function connect() {
+  if (!connectionPromise) {
+    connectionPromise = createConnection().then(newConnection => {
+      return newConnection.query("SELECT TIMEDIFF(NOW(), UTC_TIMESTAMP) AS tz").then(r => {
+        if (r[0].tz !== "00:00:00") {
+          throw new SimpleError(`Database timezone must be UTC (detected ${r[0].tz})`);
+        }
+
+        connection = newConnection;
+        return newConnection;
+      });
+    });
+  }
+
+  return connectionPromise;
+}