NOTE: database schema changed. Existing alerts will be lost.
- Unified engaged and closed tables
- Simplified hosts engaged alert counters handling: periodically set by lua
- Removed alert engine and replaced with alert periodicity
- Now engage is implicitly derived from the alert end timestamp and periodicity
- New alerts_api.lua to easily emit alerts
- Removed past alerts counter aggregation by hash
- Alert notifications for non-flow alerts are now removed from C and triggered by lua