(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.

bot/modules/guild_admin/utils/greetings.py

@@ -0,0 +1,29 @@
+import discord
+from cmdClient.Context import Context
+
+from meta import client
+
+from .settings import greeting_message, greeting_channel, returning_message
+
+
+@client.add_after_event('member_join')
+async def send_greetings(client, member):
+    guild = member.guild
+
+    returning = bool(client.data.lions.fetch((guild.id, member.id)))
+
+    # Handle greeting message
+    channel = greeting_channel.get(guild.id).value
+    if channel is not None:
+        if channel == greeting_channel.DMCHANNEL:
+            channel = member
+
+        ctx = Context(client, guild=guild, author=member)
+        if returning:
+            args = returning_message.get(guild.id).args(ctx)
+        else:
+            args = greeting_message.get(guild.id).args(ctx)
+        try:
+            await channel.send(**args)
+        except discord.HTTPException:
+            pass