Allow groups to always show user as topic source

This will allow individual groups to always show the username on topics,
overriding the usual behavior of only showing username when it's a text
topic. On Tildes itself, this will be useful for groups like ~creative.

tildes/alembic/versions/7ac1aad64144_group_add_is_user_treated_as_topic_.py

@@ -0,0 +1,36 @@
+"""Group: add is_user_treated_as_topic_source
+
+Revision ID: 7ac1aad64144
+Revises: 61f43e57679a
+Create Date: 2019-03-08 23:02:33.848382
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = "7ac1aad64144"
+down_revision = "61f43e57679a"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column(
+        "groups",
+        sa.Column(
+            "is_user_treated_as_topic_source",
+            sa.Boolean(),
+            server_default="false",
+            nullable=False,
+        ),
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column("groups", "is_user_treated_as_topic_source")
+    # ### end Alembic commands ###

tildes/tildes/models/group/group.py

@@ -47,6 +47,9 @@ class Group(DatabaseModel):
     is_admin_posting_only: bool = Column(
         Boolean, nullable=False, server_default="false"
     )
+    is_user_treated_as_topic_source: bool = Column(
+        Boolean, nullable=False, server_default="false"
+    )
 
     # Create a GiST index on path as well as the btree one that will be created by the
     # index=True/unique=True keyword args to Column above. The GiST index supports

tildes/tildes/models/topic/topic.py

@@ -452,4 +452,7 @@ class Topic(DatabaseModel):
     @property
     def is_user_treated_as_source(self) -> bool:
         """Return whether the user that posted the topic is its "source"."""
+        if self.group.is_user_treated_as_topic_source:
+            return True
+
         return self.is_text_type