drop Go versions prior to 1.7 in CI

* drop Go versions prior to 1.7 in CI

* consolidate conn*.go files after dropping old Go support

Author: adamdecaf

.travis.yml

@@ -3,9 +3,6 @@ sudo: false
 
 matrix:
   include:
-    - go: 1.4
-    - go: 1.5.x
-    - go: 1.6.x
     - go: 1.7.x
     - go: 1.8.x
     - go: 1.9.x

conn.go

@@ -370,6 +370,15 @@ func (c *Conn) writeFatal(err error) error {
 	return err
 }
 
+func (c *Conn) read(n int) ([]byte, error) {
+	p, err := c.br.Peek(n)
+	if err == io.EOF {
+		err = errUnexpectedEOF
+	}
+	c.br.Discard(len(p))
+	return p, err
+}
+
 func (c *Conn) write(frameType int, deadline time.Time, buf0, buf1 []byte) error {
 	<-c.mu
 	defer func() { c.mu <- true }()