Replace "frame" with "message" in documentation

The documentation sometimes used the term "frame" when referring to
single frame control messages.  Use the term "message" for consistency
in the documentation and to hide a detail that most application
programmers do not need to know about.

conn.go

@@ -100,7 +100,7 @@ func (e *netError) Error() string   { return e.msg }
 func (e *netError) Temporary() bool { return e.temporary }
 func (e *netError) Timeout() bool   { return e.timeout }
 
-// CloseError represents close frame.
+// CloseError represents a close message.
 type CloseError struct {
 	// Code is defined in RFC 6455, section 11.7.
 	Code int
@@ -342,7 +342,8 @@ func (c *Conn) Subprotocol() string {
 	return c.subprotocol
 }
 
-// Close closes the underlying network connection without sending or waiting for a close frame.
+// Close closes the underlying network connection without sending or waiting
+// for a close message.
 func (c *Conn) Close() error {
 	return c.conn.Close()
 }
@@ -1034,7 +1035,7 @@ func (c *Conn) SetReadDeadline(t time.Time) error {
 }
 
 // SetReadLimit sets the maximum size for a message read from the peer. If a
-// message exceeds the limit, the connection sends a close frame to the peer
+// message exceeds the limit, the connection sends a close message to the peer
 // and returns ErrReadLimit to the application.
 func (c *Conn) SetReadLimit(limit int64) {
 	c.readLimit = limit
@@ -1047,16 +1048,16 @@ func (c *Conn) CloseHandler() func(code int, text string) error {
 
 // SetCloseHandler sets the handler for close messages received from the peer.
 // The code argument to h is the received close code or CloseNoStatusReceived
-// if the close message is empty. The default close handler sends a close frame
-// back to the peer.
+// if the close message is empty. The default close handler sends a close
+// message back to the peer.
 //
 // The application must read the connection to process close messages as
-// described in the section on Control Frames above.
+// described in the section on Control Messages above.
 //
-// The connection read methods return a CloseError when a close frame is
+// The connection read methods return a CloseError when a close message is
 // received. Most applications should handle close messages as part of their
 // normal error handling. Applications should only set a close handler when the
-// application must perform some action before sending a close frame back to
+// application must perform some action before sending a close message back to
 // the peer.
 func (c *Conn) SetCloseHandler(h func(code int, text string) error) {
 	if h == nil {
@@ -1075,11 +1076,11 @@ func (c *Conn) PingHandler() func(appData string) error {
 }
 
 // SetPingHandler sets the handler for ping messages received from the peer.
-// The appData argument to h is the PING frame application data. The default
+// The appData argument to h is the PING message application data. The default
 // ping handler sends a pong to the peer.
 //
 // The application must read the connection to process ping messages as
-// described in the section on Control Frames above.
+// described in the section on Control Messages above.
 func (c *Conn) SetPingHandler(h func(appData string) error) {
 	if h == nil {
 		h = func(message string) error {
@@ -1101,11 +1102,11 @@ func (c *Conn) PongHandler() func(appData string) error {
 }
 
 // SetPongHandler sets the handler for pong messages received from the peer.
-// The appData argument to h is the PONG frame application data. The default
+// The appData argument to h is the PONG message application data. The default
 // pong handler does nothing.
 //
 // The application must read the connection to process ping messages as
-// described in the section on Control Frames above.
+// described in the section on Control Messages above.
 func (c *Conn) SetPongHandler(h func(appData string) error) {
 	if h == nil {
 		h = func(string) error { return nil }