Fix: syncing channel does not trigger event handlers

[michaelortmann]

Found by: wilkowy
Patch by: michaelortmann
Fixes: #599

One-line summary:
Fix: syncing channel does not trigger event handlers

Additional description (if needed):
When the bot joins a chan, gotjoin() creates a member for the channel member list and then it resets the chan with flags CHAN_RESETALL, removing that member again. This PR unsets flag CHAN_RESETWHO for this very case, when the member list contains 1 member, which is the bot itself that just got created.

Test cases demonstrating functionality (if applicable):
scripts/599.tcl :

proc wilktest:user_kick {nick uhost hand chan whom why} {
	putlog "#DEBUG# user_kick $nick $uhost $hand $chan $whom $why"
	if {[isbotnick $whom]} {
		putlog "#DEBUG# user_kick - me"
		return
	}
	return
}

proc wilktest:chan_mode {nick uhost hand chan mode whom} {
	putlog "#DEBUG# chan_mode $nick $uhost $hand $chan $mode $whom / [isbotnick $whom] [botisop $chan] [wasop $whom $chan] [isop $whom $chan]"
	return
}

bind kick - * wilktest:user_kick
bind mode - *+o* wilktest:chan_mode

eggdrop.conf:
source scripts/599.tcl
start eggdrop and .+chan #testchan and let it join a server
on another irc client, join #testchan before the bot and as soon as the bot joins the channel op it
Before:
The bot will see the op, but not trigger tcl:
[12:59:22] [@] :testuser!~michael@localhost MODE #testchan +o BotA
After:

[13:00:50] #testchan: mode change '+o BotA' by testuser!~michael@localhost
[13:00:50] triggering bind wilktest:chan_mode
[13:00:50] #DEBUG# chan_mode testuser ~michael@localhost * #testchan +o BotA / 1 1 0 1