packageManager to use pointer receivers everywhere

Had a problem with getting a copy because a value receiver called a
pointer receiver.
diff --git a/packet-manager.go b/packet-manager.go
index 906b3ee..8c6691c 100644
--- a/packet-manager.go
+++ b/packet-manager.go
@@ -23,8 +23,8 @@
 	working   *sync.WaitGroup
 }
 
-func newPktMgr(sender packetSender) packetManager {
-	s := packetManager{
+func newPktMgr(sender packetSender) *packetManager {
+	s := &packetManager{
 		requests:  make(chan requestPacket, SftpServerWorkerCount),
 		responses: make(chan responsePacket, SftpServerWorkerCount),
 		fini:      make(chan struct{}),
@@ -39,19 +39,19 @@
 
 // register incoming packets to be handled
 // send id of 0 for packets without id
-func (s packetManager) incomingPacket(pkt requestPacket) {
+func (s *packetManager) incomingPacket(pkt requestPacket) {
 	s.working.Add(1)
 	s.requests <- pkt // buffer == SftpServerWorkerCount
 }
 
 // register outgoing packets as being ready
-func (s packetManager) readyPacket(pkt responsePacket) {
+func (s *packetManager) readyPacket(pkt responsePacket) {
 	s.responses <- pkt
 	s.working.Done()
 }
 
 // shut down packetManager controller
-func (s packetManager) close() {
+func (s *packetManager) close() {
 	// pause until current packets are processed
 	s.working.Wait()
 	close(s.fini)
diff --git a/request-server.go b/request-server.go
index 0fc3f92..07b512c 100644
--- a/request-server.go
+++ b/request-server.go
@@ -28,7 +28,7 @@
 type RequestServer struct {
 	*serverConn
 	Handlers        Handlers
-	pktMgr          packetManager
+	pktMgr          *packetManager
 	openRequests    map[string]Request
 	openRequestLock sync.RWMutex
 	handleCount     int
diff --git a/server.go b/server.go
index 41b98e8..be14f62 100644
--- a/server.go
+++ b/server.go
@@ -29,7 +29,7 @@
 	*serverConn
 	debugStream   io.Writer
 	readOnly      bool
-	pktMgr        packetManager
+	pktMgr        *packetManager
 	openFiles     map[string]*os.File
 	openFilesLock sync.RWMutex
 	handleCount   int