[echoscu|storescu] Change SCP address parameter to enable specifying AE title

[Enet4]

This resolves #204, allowing users to specify the called AE title alongside the socket address with the optional syntax called-ae-title@socketaddress. The option called-ae-title overrides the AE title in the address with a warning. README files were updated accordingly.

CC @Almeida-a

[Almeida-a]

I would just like to note that, in the help page, the file token has the optional tag '[...]' instead of the required one '<...>'.

Is it on purpose?

[Enet4]

I would just like to note that, in the help page, the file token has the optional tag '[...]' instead of the required one '<...>'.

Is it on purpose?

Yes, the files parameter was set up to be optional by mistake. It is not a regression from this PR, so one can take care of that separately.