improvements to client_launcher

[Antoine Martin]

Important:

• it needs a man page - this is a debian requirement: all public commands (ie: /usr/bin/) need a man page, even if it is a small one that refers to another one

More minor issues:

• how do you create your config files? this needs to be documented somewhere, maybe providing an example config with comments in /usr/share/winswitch/launcher-example/
• I've removed the default values from LauncherSession to ensure they are populated correctly from file - the code should ensure the values make sense (port>0, host.len>0)
• LauncherClient should show a warning if the session fails to start
• file mime-type mapping so users can double click on them and have the software automatically launched
• dealing with ssh-tunnels (totally non-trivial)

[Arthur Huillet]

Man page is done - added in r4282

[Antoine Martin]

removed the launcher in r4282