client-conf: Avoid loading X11 properties unless SSH_CONNECTION is set
Reading properties from the X11 root window is meant to provide 1:1 results with reading the configuration directly in the local case. This configuration is essentially different only in remote cases.
Add an extra check for the SSH_CONNECTION envvar, so we don't even need opening a X11 display connection for IPC in the most usual case.
Related: #693 (closed)
Edited by Carlos Garnacho