Flats in walls

See merge request STJr/SRB2!548

Better Deadzones

See merge request STJr/SRB2!541

Choose a random port as a client

See merge request STJr/SRB2!554

This reverts commit 2a9a2c0f.

Expecting the buildbot to complain

Prints the generic "can't do this in a HUD hook" message. Whatever. I'm tired.

If you ever need to, you can change the client port number.

Using strcpy is stupid because we don't know how long the argument would be.
There's no need for a buffer anyway.