Minor modification in error message display
The client can now receive 1024 bytes at the time
The server supports now the disconnection of the client

The client does still not support the disconnection of the server ...
Delete the function sock_run
Write an error message if an operation on a non-existing curve is asked
Correct run docstring
Implement curves RAZ function
Add command line option "port" and reorganize command line help
Create an example of RT plot in the file example_rt_plot.py