Issue Description:

.21 update causes a fatal server crash since the inventory panel is using a gui class, which is client side only.

What happens:

see above.

What you expected to happen:

a running server :)

Steps to reproduce:

1.update to .21
2.start server
3.watch it crash gloriously
...

Affected Versions (Do not use "latest"):

• EnderIO: .21

Your most recent log file where the issue was present:

[pastebin/gist/etc link here]
https://pastebin.com/CvvwsUSr

Its not

Inventory Panel isn't even half-way ported yet...

I'm saying the .21 update makes my server crash, if it's not even half-way ported, why is it in the base enderio jar?