add initial socket examples: client, server

FossilOrigin-Name: 706122b5c2fc0fabeb0f694820e56963763a5855f1dcacb65c887151c106482f

example/socket-client.forth

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+This uses the new `socket:` words to download a file via Gopher.
+
+Open a file to store the data and a socket.
+
+~~~
+'Output.txt file:open<for-writing> 'File var<n>
+socket:create dup n:put nl 'Sock var<n>
+~~~
+
+Connect to the server.
+
+~~~
+'forthworks.com '70 socket:configure
+@Sock socket:connect drop
+~~~
+
+Next, send the request.
+
+~~~
+'/\n\n s:format @Sock socket:send drop-pair
+~~~
+
+After this, I can just read in the data, writing it to
+the file.
+
+~~~
+[ here #1024 @Sock socket:recv  (discard_errno: drop
+  here [ @File file:write ] s:for-each
+  dup '%n_bytes_received\n s:format s:put
+  (check_for_disconnect: n:zero? ] until
+~~~
+
+And finally, clean up by closing the socket and file.
+
+~~~
+@Sock socket:close
+@File file:close
+~~~

example/socket-server.forth

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+Get a socket.
+
+~~~
+socket:create 'Sock var<n>
+~~~
+
+Bind to port 9998.
+
+~~~
+'9998 @Sock socket:bind drop
+~~~
+
+Prepare to listen for connections.
+
+~~~
+#3 @Sock socket:listen drop-pair
+~~~
+
+Serve the user some data. This will repeat 5 times, then end.
+
+~~~
+#5 [ @Sock socket:accept (discard_error_code: drop )
+     'Hello_from_RETRO\n s:format swap [ socket:send drop-pair ] sip socket:close
+   ] times
+~~~
+
+Clean up.
+
+~~~
+@Sock socket:close
+~~~