This fixes:
[Tue Feb 16 13:50:09 2016] [error] [client 10.48.224.4] PHP Warning:  Missing argument 2 for SimpleSAML_Error_AuthSource::__construct(), called in /apps/simplesamlphp-bd-1.14.0/modules/negotiate/lib/Auth/Source/Negotiate.php on line 336 
[Tue Feb 16 13:50:09 2016] [error] [client 10.48.224.4] PHP Notice:  Undefined variable: reason in /apps/simplesamlphp-bd-1.14.0/lib/SimpleSAML/Error/AuthSource.php(31)

Avoid the PHP session handler to generate errors when we try to retrieve a session after the headers being sent to the browser.

Enhance the documentation for SimpleSAML\Locale\Language. Move all the configuration properties to the constructor, instead of the methods.

Add tests for SimpleSAML\Locale\Language::getDefaultLanguage() and fix other tests for the same class.

Template refactor rebased

Fix the calls to the old getTranslation() and getAttributeTranslation() methods from SimpleSAML_XHTML_Template.

Restore the rest of the public methods in SimpleSAML_XHTML_Template that were removed, make them wrappers of the new methods, and mark them as deprecated.

Restore SimpleSAML_XHTML_Template::getLanguageCookie() and setLanguageCookie() temporarily, as wrappers over the new methods in SimpleSAML\Locale\Language.

More bugfixes. includeLanguageFile() has been moved from SimpleSAML_XHTML_Template to SimpleSAML\Locale\Translate.

More bugfixes. The SimpleSAML\Locale\Language::$languageParameterName and SimpleSAML\Locale\Language::$language properties should be private, and therefore not accessed from the outside of their respective classes. Add getters instead.

Add a method SimpleSAML_XHTML_Template::getTranslator() to retrieve the SimpleSAML\Locale\Translate instance local to the template, and use it to fix a bug in a template of the consent module.

Bugfix. The consentAdmin module was still calling SimpleSAML_XHTML_Template::getTag(), while that method has been moved to \SimpleSAML\Locale\Translate.

Rename \SimpleSAML\Locale\Translate::t_not_translated() to the more concise (and camel caps) getStringNotTranslated().

Return lang_merge() to SimpleSAML_XHTML_Template, as it was public, and mark it as deprecated. Use array_merge_recursive() instead.

Rename \SimpleSAML\Locale\Translate::getTranslation() to the more comprehensive \SimpleSAML\Locale\Translate::getPreferredTranslation().