feat(sdam): backport unified SDAM changes from next to master

The unified SDAM will be shipped in v3.2.0 now, so this brings the
changes over the past four months into `master` for that release.

index.js

@@ -33,6 +33,7 @@ module.exports = {
   Sessions: require('./lib/sessions'),
   BSON: BSON,
   EJSON: EJSON,
+  Topology: require('./lib/sdam/topology'),
   // Raw operations
   Query: require('./lib/connection/commands').Query,
   // Auth mechanisms

lib/connection/connect.js

@@ -108,7 +108,7 @@ function performInitialHandshake(conn, options, callback) {
         options.port +
         ' reports wire version ' +
         (ismaster.maxWireVersion || 0) +
-        ', but this version of Node.js Driver requires at least ' +
+        ', but this version of the Node.js Driver requires at least ' +
         latestSupportedMaxWireVersion +
         ' (MongoDB' +
         latestSupportedVersion +

lib/connection/pool.js

@@ -742,6 +742,27 @@ Pool.prototype.destroy = function(force) {
   checkStatus();
 };
 
+/**
+ * Reset all connections of this pool
+ *
+ * @param {function} [callback]
+ */
+Pool.prototype.reset = function(callback) {
+  // this.destroy(true, err => {
+  //   if (err && typeof callback === 'function') {
+  //     callback(err, null);
+  //     return;
+  //   }
+
+  //   stateTransition(this, DISCONNECTED);
+  //   this.connect();
+
+  //   if (typeof callback === 'function') callback(null, null);
+  // });
+
+  if (typeof callback === 'function') callback();
+};
+
 // Prepare the buffer that Pool.prototype.write() uses to send to the server
 function serializeCommand(self, command, callback) {
   const originalCommandBuffer = command.toBin();