Update to TinyMCE 4.x
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
Make sure preformance info logged in devel_mode uses locale-independent number format
Merge branch 'master' of github.com:roundcube/roundcubemail
Foward locking parameter
Append group parameter to attachments set by plugins if not present
Update Changelog
Refactored storage properties setting
Merge branch 'master' of github.com:roundcube/roundcubemail
Skins sorted by skin name in the Settings.
Allow plugins to define custom attachment classes
Avoid unexpected redirects to inbox after auto-saving a draft (#1489789)
Merge branch 'master' of github.com:roundcube/roundcubemail
Fix "washing" of unicoded style attributes (#1489777)
Update changelog
Fix messages index cache update under some conditions (e.g. proxy) (#1489756)
Drop support for IE6, move IE7/IE8 support to legacy_browser plugin, update to jQuery-2.1.0
Fix subfolders margin on folders list