Fix male assassin unable to use weapons properly.

Remove zombie/gonome bullet resistance.
Make it slighly harder to gib monsters.
Small navigation fix.
Fix compilation on Visual Studio 2015 and 2017.
Fix "use_monstermod" keyvalue not working.

src/dlls/monsters.cpp

@@ -1554,7 +1554,7 @@ void CMBaseMonster :: Move ( float flInterval )
 				}
 				else
 				{
-//jlb					TaskFail();
+					TaskFail();
 					ALERT( at_aiconsole, "%s Failed to move (%d)!\n", STRING(pev->classname), HasMemory( bits_MEMORY_MOVE_FAILED ) );
 					//ALERT( at_aiconsole, "%f, %f, %f\n", pev->origin.z, (pev->origin + (vecDir * flCheckDist)).z, m_Route[m_iRouteIndex].vecLocation.z );
 				}