Fix a bug introduced in 6a614913 that made it impossible for nested EntitiesDescriptor elements to be parsed due to name spaces lost in the process.

Add statistics data to saml:idp:Response and saml:idp:Response:error
with the total time since we began processing the authentication
request.

This change makes it easier to add elements to the statistics data
logged when the IdP sends an authentication response.

Some small things found while setting up a new installation

Mark as deprecated in SimpleSAML_Utilities: validateXML(), validateXMLDocument(), validateCABuiltIn(), validateCAExec(), validateCA().

Rename SimpleSAML_Session::getInstance() to SimpleSAML_Session::getSessionFromRequest(), and leave the former as deprecated.

Mark as deprecated in SimpleSAML_Session: DATA_TIMEOUT_LOGOUT, $authority, getAuthority(), getAuthnRequest(), setAuthnRequest(), setIdP(), getIdP(), setSessionIndex(), getSessionIndex(), setNameID(), getNameID(), setSessionDuration(), remainingTime(), isAuthenticated(), getAuthnInstant(), getAttributes(), getAttribute(), setAttributes(), getSize(), expiraDataLogout(), setLogoutState(), getLogoutState().

Update the documentation for the sqlauth module, discouraging plain text passwords and adding the appropriate security considerations.

Make the search.{username | password} and priv.{username | password} LDAP options available in the authX509 module. Fix #79.

Fix call-time pass-by-reference

Update links to SSP homepage to point to simplesamlphp.org.

To support PHP >= 5.4, call-time pass-by-reference must be avoided.
See http://fr2.php.net/manual/en/language.references.pass.php

This is more than just cosmetics, as the rnd.feide.no links redirect
people to the SSP 1.5 documentation which is rather outdated.

Fix #82 and #83. Make the checks for an IDPList happen only when we are the IdP authenticating the user, not an intermediate proxy.