(and correct the display on joined tabs)

On xmltab and listtab, the help text would be displayed in the input
after closing the tab.

It’s a bit late for that, but we have to do this in order to ensure new
setting values will be used after an update if the user didn’t willingly
change them.

For consistency

(it does both by default, and is better)

also, typo

And false by default, as it might reduce the user experience in
chatrooms.

(but don’t do anything with it, leave that to plugins)

add optional muc_list to configuration of simple_notify, as a whitelist of MUCs you want to be notified from.

fix #3192

xml does not like ascii control chars.

Detecting errors would be a pain though

(broken since slix)

It was missing the highlight event

(specifically, require_encryption and log)

the require_encryption option would not be honored when opening a new
tab with a bare JID.

(caused text to align left if the message was multiline and the first
line was out of screen)

(broken in previous commit)