added to yarp write completition a single history file for each differen...

...t port

My "yarp write" use case is exit and start it again many times, I believe that having the possibility to carry history from one execution to another is fundamental, yet I didn't want to pollute each yarp write with the history of all the other opened ports. This seems a reasonable solution, notice that if the user does not have any ~/.yarp_write_history folder, nothing will happen (as it is now).