Previously events used to use class name as a prefix and ignored eo_prefix
when specified. This is no longer the case. Events follow eo_prefix by default
now. In order to get around this for classes where this is undesirable, a new
field event_prefix was added which takes priority over eo_prefix. If neither
is specified, class name is used like previously.
@feature
Jean-Philippe Andre
Daniel Kolesa
Tom Hacohen
Cedric BAIL