XEP-0065,XEP-0096,XEP-0166,XEP-0235,XEP-0300: file transfer improvments:

huge patch sorry :)

many things are improved by this patch, notably:
- updated to last protocol changes (urn:xmpp:jingle:apps:file-transfer:5 and urn:xmpp:hashes:2)
- XEP-0234: file request implementation
- XEP-0234: methods to parse and generate <file> element (can be used by other plugins easily)
- XEP-0234: range data is now in a namedtuple
- path and namespace can be specified when sending/requesting a file (not standard, but needed for file sharing)
- better error/termination handling
- trigger points to handle file requests by other plugins
- preparation to use file plugins with components

src/plugins/plugin_xep_0363.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python2
 # -*- coding: utf-8 -*-
 
-# SAT plugin for Jingle File Transfer (XEP-0363)
+# SAT plugin for HTTP File Upload (XEP-0363)
 # Copyright (C) 2009-2018 Jérôme Poisson (goffi@goffi.org)
 
 # This program is free software: you can redistribute it and/or modify