Allow bot to utilize multiple destinations at one time

[deathbybandaid]

This adds the ability to send lists of recipients to bot. say/msg/reply/notice to send the same message to multiple destinations/recipients simultaneously.

[dgw]

Leaving this be for now, as @deathbybandaid recently learned about the fact that IRC already supports sending to multiple destinations at once. That might lead to a refactor.

[deathbybandaid]

I think this is a pretty good step forward.
#1322 should probably be handled for this to be truly effective.

[deathbybandaid]

I have a good idea of what I want to do to tackle issue #1322 . I think it might be better to build that off of this, and not in this commit.

[deathbybandaid]

as per

<+dgw> you know it's probably safest to assume a default target limit of maybe 4, or even 2, if MAXTARGETS (or TARGMAX) isn't defined

I'm now going to build in a maxtargets value, and maybe by time
issue #1082 is handled, we can try to draw that value from the server capabilities

[Exirel]

It looks like there has been some change that generate a conflict, and not an easy one.

The more I think about multi-recipients, the more I believe we should not handle these cases in methods like say and alike, but instead to add new methods, like multi_say.

1. changing recipient to recipients is a breaking change, as there is no restriction on the argument to be a non-keyword one,
2. having to resort to type-sniffing is doomed to fail, for example if someone provide a tuple instead of a list, or alike
3. the most common use-case for say or reply is to reply to the sender of a trigger, and it is very unlikely that anyone want an implicit "send to multiple recipients"
4. explicit is better than implicit

So in conclusion, if you are still interested in such feature, I suggest to close this PR, and to start from the latest revision from master, and to add new methods, instead of changing existing ones.