This makes instanciating the Translate/Template-class unnecessary.

Both have been migrated to use namespaces.

Move the list of language localized names to the SimpleSAML\Locale\Language class, and make the array of languages generated by SimpleSAML_XHTML_Template::generateLanguageBar() a bit more useful.

Now works for:
new SimpleSAML_XHTML_Template($globalConfig, 'saml:sp/wrong_authncontextclassref.tpl.php');

That is, the following styles work:
* SimpleSAML_XHTML_Template($config, 'hostnames.php');
* SimpleSAML_XHTML_Template($globalConfig, 'negotiate:disable.php');

These do not:

* SimpleSAML_XHTML_Template($this->config, 'discopower:disco-tpl.php', 'disco');
* SimpleSAML_XHTML_Template($globalConfig, 'saml:sp/wrong_authncontextclassref.tpl.php');
* new SimpleSAML_XHTML_Template($config, 'metadata.php', 'admin');
* SimpleSAML_XHTML_Template($config, 'consentAdmin:consentadmin.php', 'consentAdmin:consentadmin');

Loading from themes also not in place

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.

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.

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().

Candidate for removal/rewrite

A template now has a translator-object, SimpleSAML_Locale_Translate.
This handles the existing translation system.

The translator has a language-object, SimpleSAML_Locale_Language. This
handles discovery and switching of locale.

SimpleSAML_XHTML_Template has several methods that are wrapped
translator-methods:

t()
isLanguageRTL()
getLanguageList()
getTranslation()

This way it isn't necessary to change much of the existing system.