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