Remove "got move cmd for non-existant local player X" message

It always happens at connect and could happen when a local client is removed, no reason to have printf.
Less verbose when missing sound

Before would print 4 message in developer, and 2 in non-developer. Now prints 2 in developer and 1 in non-developers.

Both OpenAL and Base sound show a message about using default sound when fails to load.
Don't call trap_R_RegisterSound each time an item is picked up

Might be an issue if it were not for the fact _all_ item sounds are registered at init.
Don't register chaingun start spin sound each time