Fix typo in comment
Add config variable 'proxy_whitelist'

HTTP headers X_FORWARDED_* and X_REAL_IP are only evaluated when
received from an IP listed in proxy_whitelist. Furthermore, only the
last non-trusted IP from X-Forwarded-For is used in place of the real
ip.

Without this, an attacker can easily spoof the headers and control the
result of the ip or ssl check.

This fixes several problems with [3a4c9f42], [4d480b36] and [a520f331] as
mentioned in #1489729.
Remove usage of $RCMAIL global variable
Accept broken vcards from Outlook that only supply ORG but not the required N or FN properties
Fixed notify/enotify extension handling
Fix possibly wrong error message when contact with the same email exists on move/copy
Prevent from js error when messages list does not exist
Fix error when spell-checking an empty text (#1489831)
Avoid popupmenus being closed when scrollbar is clicked (#1489832)
Update changelog
Merge branch 'x-forwarded-whitelist' of github.com:tribut/roundcubemail into tribut-x-forwarded-whitelist
Specify licenses in all javascript files and blocks to please LibreJS
Make identity name field optional (#1489510)
Get rid of unhelpful error message.
Revert unintentional change
Add splitter in Settings > Responses
Fix identities_level=4 handling in new_user_dialog plugin (#1489840)
CS fixes
Define globally available styles for UI buttons with icons