Revise the examples not to use the "from socket import *", and adjust

one comment in the example for clarity.

Doc/lib/libsocket.tex

@@ -426,10 +426,11 @@ socket it is listening on but on the new socket returned by
 
 \begin{verbatim}
 # Echo server program
-from socket import *
+import socket
+
 HOST = ''                 # Symbolic name meaning the local host
-PORT = 50007              # Arbitrary non-privileged server
-s = socket(AF_INET, SOCK_STREAM)
+PORT = 50007              # Arbitrary non-privileged port
+s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 s.bind((HOST, PORT))
 s.listen(1)
 conn, addr = s.accept()
@@ -443,10 +444,11 @@ conn.close()
 
 \begin{verbatim}
 # Echo client program
-from socket import *
+import socket
+
 HOST = 'daring.cwi.nl'    # The remote host
 PORT = 50007              # The same port as used by the server
-s = socket(AF_INET, SOCK_STREAM)
+s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 s.connect((HOST, PORT))
 s.send('Hello, world')
 data = s.recv(1024)