Fix unloading scenarios with Map.c or System.ocg scripts (#1778)

Destruction order matters!

src/game/C4Game.cpp

@@ -578,6 +578,7 @@ void C4Game::Clear()
 	// Clear the particles before cleaning up the objects.
 	Particles.Clear();
 	DeleteObjects(true);
+	::MapScript.Clear();
 	::Definitions.Clear();
 	Landscape.Clear();
 	PXS.Clear();
@@ -589,7 +590,6 @@ void C4Game::Clear()
 	Info.Clear();
 	Title.Clear();
 	pScenarioObjectsScript = NULL;
-	::MapScript.Clear();
 	::GameScript.Clear();
 	Names.Clear();
 	GameText.Clear();

src/landscape/C4MapScript.cpp

@@ -703,9 +703,9 @@ bool C4MapScriptHost::LoadData(const char * f, const char * d, C4LangStringTable
 
 void C4MapScriptHost::Clear()
 {
+	C4ScriptHost::Clear();
 	delete LayerPrototype; delete MapPrototype;
 	LayerPrototype = MapPrototype = NULL;
-	C4ScriptHost::Clear();
 }
 
 C4PropListStatic * C4MapScriptHost::GetPropList()

src/script/C4ScriptHost.cpp

@@ -229,8 +229,14 @@ C4ExtraScriptHost::C4ExtraScriptHost(C4String *parent_key_name):
 {
 }
 
+C4ExtraScriptHost::~C4ExtraScriptHost()
+{
+	Clear();
+}
+
 void C4ExtraScriptHost::Clear()
 {
+	C4ScriptHost::Clear();
 	ParserPropList._getPropList()->Clear();
 }
 

src/script/C4ScriptHost.h

@@ -100,6 +100,7 @@ class C4ExtraScriptHost: public C4ScriptHost
 	C4Value ParserPropList;
 public:
 	C4ExtraScriptHost(C4String *parent_key_name = NULL);
+	~C4ExtraScriptHost();
 	void Clear();
 
 	bool Delete() { return true; }