performance in jid : replace __getattr__ et __setattr__ by @property and @xxx.setter

this implementatian is much more verbose but faster, especilally if you are dealing a lot with JIDs
on my box, ./testall.py now takes 45s. It takes 53s in the old implementation (about 15% faster)
Bump version to 1.1.13-MBS
tostring.escape : optimization

use of xml.etree.ElementTree._escape_attrib and xml.etree.ElementTree._escape_cdata
Bump version to 1.1.14-MBS
escape: imports at the top
escape: use xml.etree.ElementTree._escape_attrib to avoid duplication
log.debug: dont log if we are not in debug mode
log.debug: cache log.isEnabledFor(logging.DEBUG) at import time
Merge branch 'noLogInDebug' of github.com:barreverte/SleekXMPP into noLogInDebug