(WIP) Eat payload of UnrealIRCd channel mode +f

[michaelortmann]

Found by: Lord255
Patch by: michaelortmann
Fixes: #1246

One-line summary:
Eat payload of UnrealIRCd channel mode +f so it does not clobber payloads of +k and / or +l

Additional description (if needed):
When eggdrop parses the channel mode line (numeric 324) it splits it at whitespace. first word is mode chars, next words are payloads.
example: +fl [10j]:15 42" has got 2 payloads, one for f and one for l
It parses the mode chars one by one.
Any unknown mode char is skipped.
Some known modes like +k and +l have payloads.
When eggdrop handles those mode chars, it will eat the next payload.
+f is an unknown mode, so the f char is ignored, so far so good.
But +f also has a payload.
If that payload is not eaten, it would be eaten as the payload for the next known mode char with payload and BOOM!
This PR makes eggdrop eat the +f payload, so that the next known mode with payload will eat the right payload and not the +f payload.

This Issue is also interesting in that it doesnt fail or log an error trying to read an integer payload for +l, when it got a string payload for +f. More reason to not use atoi() and get #1583 fixed.

See also: https://www.unrealircd.org/docs/Channel_anti-flood_settings

Test cases demonstrating functionality (if applicable):
ircII client:
*** Mode for channel #foo is "+fl [10j]:15 42"
UnrealIRCd 6.1.2.3 server:
Before:

[04:51:14] [@] :irc.example.org 324 BotA #foo +fl [10j]:15 42
[...]
.channel
[...]
Channel #foo, 2 members, mode +:

After:

[04:55:26] [@] :irc.example.org 324 BotA #foo +fl [10j]:15 42
[...]
.channel
[...]
Channel #foo, 2 members, mode +l 42:

[michaelortmann]

So far, this PR only fixes got324()

There is probably more to do to fix all +f mode fallout, but its a beginning and can be reviewed merged as is. We can do followup Issues / PRs. The original Issue looks like it describes several different bugs regarding +f.

[michaelortmann]

We could also think about adding full / proper +f support, so the bot can set it, if there is enough interest in such new feature.

[Robby-]

The proper solution, but is probably much more work, is parsing 005 to get all the modes that have "payloads", because there's a bunch more than just +f. On InspIRCd there's for example also +B, +E, +F, +j and so on, and it also has a +f but with a different payload syntax.