Issue Description:

PacketNoSpamChat's handler doesn't seem to schedule itself on the main thread. Instead, it adds to chat on the current thread.

What happens:

Crash with a ConcurrentModificationException when rendering the chat (from tabbychat).

I wrote some code to catch it, so now the stacktrace is more useful.
https://gist.github.com/killjoy1221/efede90225e4511a03a483a602dddfe6

It's been fixed on my side, but it's gonna spam the log with stacktraces each time it happens outside the minecraft thread.

Steps to reproduce:

1. Install TabbyChat
2. Hold right click with a sigil on the blood altar

Affected Versions (Do not use "latest"):

• BloodMagic: commit: 11fe41c (It's been seen in 1.8)
• Minecraft: 1.11.2
• Forge: 13.20.0.2226