Refactor files related to the Compose page and frio theme settings

- Use dependencies instead of most DI calls in Module\Item\Compose
- Group translation strings in a subkey of the template variables array
- Rewrite array initializations in theme/frio/config

src/Content/Conversation.php

@@ -328,7 +328,7 @@ class Conversation
 			$created_at = '';
 		}
 
-		$tpl = Renderer::getMarkupTemplate("jot.tpl");
+		$tpl = Renderer::getMarkupTemplate('jot.tpl');
 
 		$o .= Renderer::replaceMacros($tpl, [
 			'$new_post'            => $this->l10n->t('New Post'),