Deprecate the GetLocale class and replace with ACL\Login locales set

If ACL\Login is used, the loginGetLocale() call should be used to fetch
the locale data set during login

Language\L10n now has new encoding/charset optional parameter 4
If the locale does not have a charset set the defautl charset is UTF-8
unless set via the new parameter or setOverrideEncoding()

Because of the deprecation of the getLocales call the following methods
do no longer need $locales
- Admin\Backend
- Admin\EditBase
- Output\Form\Generate
- Template\SmartyExtend

They all use the new l10n->getLocaleAsArray() call to set all the local
variables

* Admin\EditBase has new parameter "options" to set
- cache_id
- compile_id
which must be passed on the SmartyExtend class init

vendor/phpstan/phpstan-deprecation-rules/README.md

@@ -0,0 +1,38 @@
+# Rules for detecting usage of deprecated classes, methods, properties, constants and traits.
+
+[![Build](https://github.com/phpstan/phpstan-deprecation-rules/workflows/Build/badge.svg)](https://github.com/phpstan/phpstan-deprecation-rules/actions)
+[![Latest Stable Version](https://poser.pugx.org/phpstan/phpstan-deprecation-rules/v/stable)](https://packagist.org/packages/phpstan/phpstan-deprecation-rules)
+[![License](https://poser.pugx.org/phpstan/phpstan-deprecation-rules/license)](https://packagist.org/packages/phpstan/phpstan-deprecation-rules)
+
+* [PHPStan](https://phpstan.org/)
+
+## Installation
+
+To use this extension, require it in [Composer](https://getcomposer.org/):
+
+```
+composer require --dev phpstan/phpstan-deprecation-rules
+```
+
+If you also install [phpstan/extension-installer](https://github.com/phpstan/extension-installer) then you're all set!
+
+<details>
+  <summary>Manual installation</summary>
+
+If you don't want to use `phpstan/extension-installer`, include rules.neon in your project's PHPStan config:
+
+```
+includes:
+    - vendor/phpstan/phpstan-deprecation-rules/rules.neon
+```
+</details>
+
+## Deprecating code you don't own
+
+This extension emits deprecation warnings on code, which uses properties/functions/methods/classes which are annotated as `@deprecated`.
+
+In case you don't own the code which you want to be considered deprecated, use [PHPStan Stub Files](https://phpstan.org/user-guide/stub-files) to declare deprecations for vendor files like:
+```
+/** @deprecated */
+class ThirdPartyClass {}
+```