Enable more compiler warnings and treat them as errors.

src/ActorMultiVertex.cpp

@@ -401,9 +401,9 @@ CubicSplineN* ActorMultiVertex::GetSpline(size_t i)
 	return &(_splines[i]);
 }
 
-void ActorMultiVertex::SetState(size_t i)
+void ActorMultiVertex::SetState(int i)
 {
-	ASSERT(i < _states.size());
+	ASSERT(i >= 0 and static_cast<size_t>(i) < _states.size());
 	_cur_state= i;
 	_secs_into_state= 0.0f;
 }
@@ -1002,7 +1002,7 @@ public:
 	static size_t ValidStateIndex(T* p, lua_State *L, int pos)
 	{
 		int index= IArg(pos)-1;
-		if(index < 0 || static_cast<size_t>(index) >= p->GetNumStates())
+		if(index < 0 || index >= p->GetNumStates())
 		{
 			luaL_error(L, "Invalid state index %d.", index+1);
 		}