[CSM] Client side modding

* rename GameScripting to ServerScripting
* Make getBuiltinLuaPath static serverside
* Add on_shutdown callback
* Add on_receiving_chat_message & on_sending_chat_message callbacks
* ScriptApiBase: use IGameDef instead of Server
  This permits to share common attribute between client & server
* Enable mod security in client side modding without conditions

src/client.h

@@ -305,6 +305,8 @@ private:
 	std::map<u16, u16> m_packets;
 };
 
+class ClientScripting;
+
 class Client : public con::PeerHandler, public InventoryManager, public IGameDef
 {
 public:
@@ -328,6 +330,8 @@ public:
 
 	~Client();
 
+	void initMods();
+
 	/*
 	 request all threads managed by client to be stopped
 	 */
@@ -428,6 +432,10 @@ public:
 	ClientEnvironment& getEnv() { return m_env; }
 	ITextureSource *tsrc() { return getTextureSource(); }
 	ISoundManager *sound() { return getSoundManager(); }
+	static const std::string getBuiltinLuaPath();
+
+	virtual const std::vector<ModSpec> &getMods() const;
+	virtual const ModSpec* getModSpec(const std::string &modname) const;
 
 	// Causes urgent mesh updates (unlike Map::add/removeNodeWithEvent)
 	void removeNode(v3s16 p);
@@ -692,6 +700,8 @@ private:
 	bool m_cache_enable_shaders;
 	bool m_cache_use_tangent_vertices;
 
+	ClientScripting *m_script;
+
 	DISABLE_CLASS_COPY(Client);
 };