use type coercion and less 'arguments' usage

lib/imap.js

@@ -730,10 +730,6 @@ ImapConnection.prototype.status = function(boxName, cb) {
 };
 
 ImapConnection.prototype.removeDeleted = function(cb) {
-  if (this._state.status !== STATES.BOXSELECTED)
-    throw new Error('No mailbox is currently selected');
-  cb = arguments[arguments.length - 1];
-
   this._send('EXPUNGE', cb);
 };
 
@@ -746,35 +742,24 @@ ImapConnection.prototype.getBoxes = function(namespace, cb) {
 };
 
 ImapConnection.prototype.addBox = function(name, cb) {
-  cb = arguments[arguments.length - 1];
-  if (typeof name !== 'string' || name.length === 0)
-    throw new Error('Mailbox name must be a string describing the full path'
-                    + ' of a new mailbox to be created');
-  this._send('CREATE "' + utils.escape(utf7.encode(name)) + '"', cb);
+  this._send('CREATE "' + utils.escape(utf7.encode(''+name)) + '"', cb);
 };
 
 ImapConnection.prototype.delBox = function(name, cb) {
-  cb = arguments[arguments.length - 1];
-  if (typeof name !== 'string' || name.length === 0)
-    throw new Error('Mailbox name must be a string describing the full path'
-                    + ' of an existing mailbox to be deleted');
-  this._send('DELETE "' + utils.escape(name) + '"', cb);
+  this._send('DELETE "' + utils.escape(''+name) + '"', cb);
 };
 
 ImapConnection.prototype.renameBox = function(oldname, newname, cb) {
-  cb = arguments[arguments.length - 1];
-  if (typeof oldname !== 'string' || oldname.length === 0)
-    throw new Error('Old mailbox name must be a string describing the full path'
-                    + ' of an existing mailbox to be renamed');
-  else if (typeof newname !== 'string' || newname.length === 0)
-    throw new Error('New mailbox name must be a string describing the full path'
-                    + ' of a new mailbox to be renamed to');
   if (this._state.status === STATES.BOXSELECTED
       && oldname === this._state.box.name && oldname !== 'INBOX')
-    this._state.box._newName = oldname;
+    this._state.box._newName = ''+oldname;
 
-  this._send('RENAME "' + utils.escape(oldname) + '" "' + utils.escape(newname)
-             + '"', cb);
+  var cmd = 'RENAME "';
+  cmd += utils.escape(''+oldname);
+  cmd += '" "';
+  cmd += utils.escape(''+newname);
+  cmd += '"';
+  this._send(cmd, cb);
 };
 
 ImapConnection.prototype.append = function(data, options, cb) {