#199 - Incorrect messages deleted after entity delete.

#193 - Queue purge of old messages.

#198 - Use queue system to delete messages after entity delete.

#190 - Simplifies template creation trait.

EntityTypeManager throws error because form class is not defined

Fix confusion about the difference between a message and a message template

Fixed typo in message after bulk deletion of messages.

Add configure route to .info.yml.

Fixes Example module misses depencency on Comment module #170

- Fixes #152

Run tests on PHP 7.1.

- Fixes #179

Fix non-numeric value warning on PHP 7.1

Fix for updated coding standards.

- Fixes #177

Whenever I edit a message template I am getting multiple instances of the following warning on PHP 7.1:

```
Warning: A non-numeric value encountered in Drupal\Core\Render\Element::children() (line 95 of core/lib/Drupal/Core/Render/Element.php).
Drupal\Core\Render\Element::children(Array) (Line: 999)
Drupal\Core\Form\FormBuilder->doBuildForm('message_template_edit_form', Array, Object) (Line: 1045)
Drupal\Core\Form\FormBuilder->doBuildForm('message_template_edit_form', Array, Object) (Line: 1045)
Drupal\Core\Form\FormBuilder->doBuildForm('message_template_edit_form', Array, Object) (Line: 557)
Drupal\Core\Form\FormBuilder->processForm('message_template_edit_form', Array, Object) (Line: 314)
Drupal\Core\Form\FormBuilder->buildForm('message_template_edit_form', Object) (Line: 74)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 618)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
call_user_func_array(Object, Array) (Line: 144)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 64)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 57)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 99)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 78)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 50)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 656)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)
```

This is because the weight is initialized to an empty string, but the weight should always be an integer value since it is used in numeric calculations.

Update version of core for testing

Refactors partials in build arrays.

- Fixes #167

HTML formatting is lost when delivering the message to user inbox.

Check language before getting overrides

Fix message partial handling so that correct langcode is used.

Fix for code sniffer fail