Made forum posting possible.

It has some limitations, though, as
ForumTopic.last_post and ForumTopicGroup.last_post is not updated
automagically...

src/KekRozsak/FrontBundle/Resources/config/doctrine/ForumTopic.orm.yml

@@ -40,6 +40,12 @@ KekRozsak\FrontBundle\Entity\ForumTopic:
                         targetEntity: ForumTopicGroup
                         inversedBy: topics
                         nullable: false
+        oneToOne:
+                last_post:
+                        targetEntity: ForumPost
+                        nullable: true
+                        default: null
+                        cascade: [ persist ]
         uniqueConstraint:
                 uniqueSlugByGroup:
                         columns: [ topic_group, slug ]

src/KekRozsak/FrontBundle/Resources/config/doctrine/ForumTopicGroup.orm.yml

@@ -32,6 +32,12 @@ KekRozsak\FrontBundle\Entity\ForumTopicGroup:
                         targetEntity: User
                         nullable: true
                         default: null
+        oneToOne:
+                last_post:
+                        targetEntity: ForumPost
+                        nullable: true
+                        default: null
+                        cascade: [ persist ]
         oneToMany:
                 topics:
                         targetEntity: ForumTopic