Merge drop and keepends kwargs

[MrQubo]

recvuntil() uses drop kwarg, while recvline() and recvlines() use keepends. keepends is a logical negation of drop, while both serve the same purpose. I find this unnecessarily confusing.

I would like to propose using the same kwarg for the purpose of those functions.

It's a matter of discussion whether drop or keepends or maybe a new different keyword is better.

The new keyword can be added while preserving the old behaviour.

[peace-maker]

I agree it's better to have them consistent. We could just support both drop and keepends in both functions too :D
I'm in favor of drop since keepends doesn't make much sense for recvuntil.

[sanjitkumar2016]

In my opinion, this one is a bit tricky because changing/removing kwargs ruins backwards compatibility for everyone using the keepends kwarg. The keepends kwarg is also used much more than the drop kwarg, so I'm not sure if this is something that a lot of users would expect. Supporting a both could also be weird/conflicting if a user sets both kwargs to the same values (even though they're supposed to be opposites). If we do want to remove the keepends kwarg, we could start off by issuing a Deprecation warning in the code and then implementing the changes in a future release, and raising an exception if keepends is used. Please let me know your thoughts!