Original XMPPHP is no longer maintained
Therefore I've done some optimizations and imported some commits from birkner and zorn-v forks.
None of the forks really looked ready to be adopted...
lib/plugin.php now has a parent onAutoload function that finds most common
files that are used in plugins (actions, dataobjects, forms, libs etc.) if
they are put in the standardised directories ('actions', 'classes', 'forms',
'lib' and perhaps some others in the future).
