Add more extended channel flags (XCF) (#67)

Add more extended channel flags (XCF) (#67)

* Add nick!user@host to the spamfilter warnings

This will make it easier for our mass akill scripts.

-Kobi.

* Cosmetic changes to the spamfilter warning

The warning will now say if the spammer was blocked, akilled or blocked+akilled.

-Kobi.

* Add MAX_INVITES XCF

This will let us increase the maximum invite list for specific channels.
The use case is regional channels that want to +I their region/country's IPs and use it in combination with cmode +R.

* Add HIDE_MODE_LISTS XCF

This will let us hide /mode #channel +b/+I/+e lists from non-ops.

There are a few use cases for this (especially when the list limits are increased for channels that are being regularly flooded):
1. Prevent users from disconnecting themselves for "SendQ Exceeded".
2. Prevent abusers from flooding the server with it.
3. Prevent abusers from knowing our flood-control exemption lists.

* Add USER_VERBOSE XCF

When enabled, the server will alert #channel-relay about failed commands due to channel modes or xflags.

This feature was suggested by Sara_Ks.

* Add OPER_VERBOSE XCF

When enabled, the server will alert +f opers about failed commands due to channel modes or xflags.

Similar to USER_VERBOSE but will combine all "relay channels" to one place for opers and will show the user's real hostname even if they have user host-masking enabled.

* Add FLOODWARN module hook

CHOOK_FLOODWARN is called during flood warnings to opers.

Params: 5: (aClient *source, aChannel *channel, int type, char *cmd, char *reason)

Returns: int (FLUSH_BUFFER would prevent the normal message from being sent)

* Don't verbose opers about +j failed joins

They will be getting these warnings from the throttles anyway.