patch 7.4.1244

Problem:    The channel functions don't sort together.
Solution:   Use a common "ch_" prefix.

runtime/tools/demoserver.py

@@ -1,15 +1,21 @@
 #!/usr/bin/python
+#
 # Server that will accept connections from a Vim channel.
 # Run this server and then in Vim you can open the channel:
-#  :let handle = connect('localhost:8765', 'json')
+#  :let handle = ch_open('localhost:8765', 'json')
 #
 # Then Vim can send requests to the server:
-#  :let response = sendexpr(handle, 'hello!')
+#  :let response = ch_sendexpr(handle, 'hello!')
 #
 # And you can control Vim by typing a JSON message here, e.g.:
 #   ["ex","echo 'hi there'"]
 #
+# There is no prompt, just type a line and press Enter.
+# To exit cleanly type "quit<Enter>".
+#
 # See ":help channel-demo" in Vim.
+#
+# This requires Python 2.6 or later.
 
 from __future__ import print_function
 import json