[event] consolidating timers & watches - use flags to remove deleted timers (same as watches)
[event] timers & watches consolidation - unify external event structs
[event] consolidate timers & watches - single "event_id"
[event] consolidate watches & timers - single event_internal_t structure
[event] timer_list -> timers
[event] consolidate watches & timers - single purge function