allow mnemonics for execution context levels

scriptcontext and isolatecontext now allow plain text mnemonics for
context level arguments (one of CORE, CFG, PROMPT, MAPCFG, MDLCFG)

also:

- cleanup (some dead code and dead prototypes removed)
- some stuff renamed
- script errors now show context levels
- conc is no longer thread-safe (but slightly faster)

DOCREF scriptcontext isolatecontext

source/src/serverbrowser.cpp

@@ -285,8 +285,6 @@ vector<serverinfo *> servers;
 ENetSocket pingsock = ENET_SOCKET_NULL;
 int lastinfo = 0;
 
-char *getservername(int n) { return servers[n]->name; }
-
 serverinfo *findserverinfo(ENetAddress address)
 {
     loopv(servers) if(servers[i]->address.host == address.host && servers[i]->port == address.port) return servers[i];