(guild admin): Add greeting messages.

New `SettingType` `Message` for general message settings.
New setting `greeting_message`.
New setting `greeting_channel`.
New setting `starting_funds`.
New setting `returning_message`.
Add a greeting message hook.
Add initial funds on lion creation.
Data migration v3 -> v4.

data/migration/v3-v4/migration.sql

@@ -0,0 +1,7 @@
+ALTER TABLE guild_config
+  ADD COLUMN greeting_channel BIGINT,
+  ADD COLUMN greeting_message TEXT,
+  ADD COLUMN returning_message TEXT,
+  ADD COLUMN starting_funds INTEGER;
+
+INSERT INTO VersionHistory (version, author) VALUES (4, 'v3-v4 Migration');

data/schema.sql

@@ -72,7 +72,11 @@ CREATE TABLE guild_config(
   accountability_reward INTEGER,
   accountability_price INTEGER,
   video_studyban BOOLEAN,
-  video_grace_period INTEGER
+  video_grace_period INTEGER,
+  greeting_channel BIGINT,
+  greeting_message TEXT,
+  returning_message TEXT,
+  starting_funds INTEGER
 );
 
 CREATE TABLE ignored_members(