rename listener to subscriber

[greg0ire]

This PR renames listener classes to SomethingSubscriber. There are still some "listener" occurences in the README and in the DIC file, but I think changing them would be a BC-break.

[docteurklein]

That would indeed be a BC break for those who manually defined services for them (or extended them, which shouldn't be done actually).

One solution would be to provide a temporary set of classes (that extends subscriber) and named like before. their ctor would raise a E_DEPRECATED warning.

[greg0ire]

@docteurklein : I was more thinking about people using the DIC to inject services defined in your file, but after a closer look, I can see that you marked them as private, so there is no problem. Regarding the name of the classes, I don't think it is a BC-break : these classes are not part of your public API (which you could tag), they are used internally to do things. That's not like if we renamed the traits. I think you can merge this safely.

[docteurklein]

right, lets merge it and note the renamings the UPGRADE.md file.

[docteurklein]

could you add a UPGRADE.md file ?

[greg0ire]

@docteurklein : with a 1.0.1 to 1.0.2 § ? I'll add it, but not now, because I think the private services could and should be renamed first, do you agree ? Plus, I'm a bit busy right now.

[docteurklein]

right we can add it later

[greg0ire]

Ok, I'll try to do it tomorrow if I can.