default session_lifetime is 24hrs
recreation of session is triggered at 50% of the session life time

clarify documentation. Fixes https://github.com/owncloud/core/issues/2624 

see #2568

Required by several applications like our pdf viewer

Add support for a reverse proxy that only forwards SSL connections
unencrypted to the web server.

This patch allows to detect the reverse proxy via regular expression for
the remote IP address and conditional overwrite the host name, protocol
and web root.

Add support for a reverse proxy that handles multiple domains via different
web roots (http[s]://proxy.tld/domain.tld/owncloud).

As the reverse proxy web root is transparent for the web server the
REQUEST_URI and SCRIPT_NAME need manual adjustments. This patch replace
the direct use of this _SERVER variables with function calls and extend
this functions to overwrite the web root. Additionally it adds a Sabre
request backend that extends the Sabre_HTTP_Request to use the same
functions.

added parameter mail_smtpauthtype to set SMTP authentication type. 

The debug mode should not be enabled in productive environments and is also a security risk since some apps outputs unsanitized debug data to the template.

fixed an other typo.

Fixed type in line 70. Thank you for pointing me to that typo.

Added three additional mail_smtp.. parameters.
- mail_smtpdebug - enable debug messages to analyse SMTP problems.
- mail_smtptimeout - set SMTP timeout which is set to 10s by
  default and this is sometimes to short especially if a malware/
  spam scanner is used.
- mail_smtpsecure - force secure SMTP connections.

Let's remove it, it's also not secure anymore with the introduction of
our API etc...
(And doesn't work with ldap etc…)

Thanks Bart for the hint.
This also switches "==" to "<>" and not the code actually works ;-)

https://github.com/owncloud/core/issues/504