coretasks: NAMESX when multi-prefix is not available

[Exirel]

Description

As per the discussion in #1496 this makes Sopel send a PROTOCTL NAMESX command when:

1. we receive a RPL_ISUPPORT message from the server
2. multi-prefix is not an available capability
3. NAMESX is now activated

Checklist

• I have read CONTRIBUTING.md
• I can and do license this contribution under the EFLv2
• No issues are reported by make qa (runs make quality and make test)
• I have tested the functionality of the things this change touches

[dgw]

The actual implementation of this is so stupidly simple that I can't imagine why I didn't think of this approach when I dug into NAMESX stuff a month ago. Of course it works to check if the bot already knows about NAMESX being advertised. Big brain time!

Just editing the comments like I do. One of them reminded me of a very rude meme phrase starting, "Do you are have" and ending with an insult, so I had to fix. x)

[dgw]

So I just thought of a different way to write the comments added to handle_isupport() but it's not enough of an improvement to bother.

Are you planning to work on the WHOX part of #1496? If you are, I should merge this next (like later tonight when Travis' queue is shorter) so you can build on it.

[Exirel]

Are you planning to work on the WHOX part of #1496? If you are, I should merge this next (like later tonight when Travis' queue is shorter) so you can build on it.

Not really. I don't get how WHOX is supposed to work (yet). Maybe another time!

[dgw]

OK, one of us will look at WHOX in the coming weeks. I tweaked how Sopel detects WHOX availability in #1998, for a start. Need more research before going any further, but not sure when I'll get the time to do that. Probably next (not this coming) weekend, at the earliest, and I have doubts about that timeline. It's gonna be a busy month. :-/