These functions let you pass an array of callbacks instead of just one.
It's more memory efficient to use this if you just add a bulk of events
on the same object.
This commits breaks ABI, and breaks API of the EO_EV_CALLBACK_ADD/DEL
signals (the event info passed).
We now need to pass the current class to eo_do_super. This is faster and
more memory efficient and generally lets us do things better.
Using the eo_benchmarks we get ~20% speed-up.
This was stupid from the start, but now it casuse even more issues.
We'll have to just add a configure option to it when the time comes.
SVN revision: 82989