Revert "Peer timer teardown"

This reverts commit d73f960aab.

Problems with deadlocking arises due to orphaned packets in per-peer
queues. Additional work on this issue continues in seperate branch.

src/timer.go

@@ -43,6 +43,12 @@ func (t *Timer) Reset(dur time.Duration) {
 	t.Start(dur)
 }
 
+func (t *Timer) Push(dur time.Duration) {
+	if t.pending.Get() {
+		t.Reset(dur)
+	}
+}
+
 func (t *Timer) Wait() <-chan time.Time {
 	return t.timer.C
 }