[Quake-C] Safe spawn calc for Shambler in Runequake

[Cobalt <co...@te...>]

Been messing with this issue for a long while, have made some progress but 
because there is no tracebox built-in on the engine we are using (Manquake) 
which is a Proquake derivitave, its been harder than expected.

Basicly the original code merely spawns a Shambler monster at the players 
origin, mo matter where they are. If theres not enough space, the Shamblers 
stuck in the wall. There is a Walkmove (0,0) check done someplace to try and 
help fix the issue but its not always being called at the right times.

Decided to redo the entire system with some code another Quaker made which 
is basicly doing what tracebox does but slightly different. Im doing this 
check alot, and since its using tracelines, and the code Im calling it from 
is basicly a while loop with more tracelines, I believe I am tripping the 
runaway loop counter so the eng crashes.

If someone could take a look and maybe make some sugguestions, or even a 
completely new way of doing it, would appreciate it. Basicly the main 
function
being called is: Rune_ShamblerReloc ()  on line 449 here in this file:
https://github.com/odnarb/runequake/blob/master/src/runes40.qc

The compiler being used is I believe qccx which is very old, so we have to 
use 'old fashioned' style Quake C for the time being.