Imported changes
Work on functionDefinition
Work on events
Work on functionDefinition
Work on events
declaration rule is now OK with events
Protect against eventual emtpy topic data
Fixed deref action and do not return flags data
Scope fix
Revisited scope management
General fixes

* Give level in logging
* Do not erase a topic level data if already setted outside the control
of Callback package
* Support of method_void flag
* Rename sub topic_data to topic_level_fired_data to clearly indicate
this is a level-aware routine
* Change the order of arguments to routine reset_topic_fired_data,
putting eventual level at the end
Removed unused methods and did few renamings
A little more information in the log
Use explicit ($start, $length) for readibility
New attribute extra_description, mainly for better logging
functionDefinition checks
Work on events
functionDefinition
use Marpa::R2 2.061001 and its terminals_expected
Work on functionDefinition, simplified some calls