Rename the xmpp-parsers directory to parsers

This doesn’t change anything to the name of the crate, just makes
autocompletion easier by not sharing the same prefix as the xmpp crate.

xmpp-parsers/src/muc/mod.rs

@@ -1,14 +0,0 @@
-// Copyright (c) 2017 Maxime “pep” Buquet <pep@bouah.net>
-//
-// This Source Code Form is subject to the terms of the Mozilla Public
-// License, v. 2.0. If a copy of the MPL was not distributed with this
-// file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-/// The http://jabber.org/protocol/muc protocol.
-pub mod muc;
-
-/// The http://jabber.org/protocol/muc#user protocol.
-pub mod user;
-
-pub use self::muc::Muc;
-pub use self::user::MucUser;