[feature] Prune timelines once per hour to plug memory leak (#1117)

* export highest/lowest ULIDs as proper const

* add stop + start to timeline manager, other small fixes

* unexport unused interface funcs + tidy up

* add LastGot func

* add timeline Prune function

* test prune

* update lastGot

internal/processing/processor.go

@@ -351,6 +351,11 @@ func (p *processor) Start() error {
 		return err
 	}
 
+	// Start status timelines
+	if err := p.statusTimelines.Start(); err != nil {
+		return err
+	}
+
 	return nil
 }
 
@@ -359,8 +364,14 @@ func (p *processor) Stop() error {
 	if err := p.clientWorker.Stop(); err != nil {
 		return err
 	}
+
 	if err := p.fedWorker.Stop(); err != nil {
 		return err
 	}
+
+	if err := p.statusTimelines.Stop(); err != nil {
+		return err
+	}
+
 	return nil
 }