Fixed|Client: Excessive server list updating

The client was updating the MPI server list whenever the Beacon
got a local server's response, even if the UI was not active or not
in the custom search mode.
Hexen|Debug: Cleanup

A fatal error in the mobj saver, oh my. Probably meant to be an
assert? Triggered this when saving the game right after killing
Korax in the end of Hexen.
Fixed|Client|Hexen: Duplicated Fighter weapon effects