Change: Limit memory allocations for each Squirrel instance

This can avoid out-of-memory situations due to single scripts using up the entire address space.
Instead, scripts that go above the maximum are killed.
The maximum is default 1 GB per script, but can be configured by a setting.

src/script/script_instance.cpp

@@ -153,6 +153,8 @@ void ScriptInstance::Died()
 	DEBUG(script, 0, "The script died unexpectedly.");
 	this->is_dead = true;
 
+	this->last_allocated_memory = this->GetAllocatedMemory(); // Update cache
+
 	if (this->instance != nullptr) this->engine->ReleaseObject(this->instance);
 	delete this->engine;
 	this->instance = nullptr;
@@ -698,3 +700,9 @@ void ScriptInstance::InsertEvent(class ScriptEvent *event)
 
 	ScriptEventController::InsertEvent(event);
 }
+
+size_t ScriptInstance::GetAllocatedMemory() const
+{
+	if (this->engine == nullptr) return this->last_allocated_memory;
+	return this->engine->GetAllocatedMemory();
+}