Do not try to connect tcp or command port if not needed

[bignaux]

Currently, ps2client always try to connect both server instead of connecting according to the commands.

https://github.com/ps2dev/ps2client/blob/master/src/ps2link.c#L44-L59
Refactoring a bit would avoid useless connection and simplify the addition of new command.

[fjtrujy]

Probably we could have a flag in the config file for enable/disable this