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people to the SSP 1.5 documentation which is rather outdated.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.

Set WantAuthnRequestsSigned in the generated IdP XML metadata if validate.authnrequest or redirect.validate options are set in saml20-idp-hosted metadata (with that order of precedence). Fixes #43.

Match WantAuthnRequestsSigned to 'sign.authnrequest' option instead of 'redirect.sign' when parsing IdP metadata.

Fail gracefully while parsing EntitiesDescriptor in the metarefresh module. Now only the offending entity is disregarded. Fixes #70.

Give absolute priority to mdui:DisplayName for the 'name' field when parsing XML metadata. Solves #54.

Remove 'saml2.relaxvalidation' option from documentation. This feature was removed back in 2009. Fixes #78.

Blacklist 'http://www.w3.org/2001/04/xmlenc#rsa-1_5' (RSA encryption with PKCS#1 v1.5 padding) by default.

Reformat the logging classes. Extract the LoggingHandler to its own file. Add proper documentation. Fix typos.

Merge branch 'translation' of https://github.com/JanOppolzer/simplesamlphp into JanOppolzer-translation