Allow to mark preferences as immutable or deprecated

- Deprecated: The option is read from the settings, but not written back
  when saving. This can be used for migrating options to a new name or
  format. (Not used yet.)
- Immutable: The option can not be changed from Lua. Used for
  security-relevant options that should not be changable by the theme or
  mod charts. Currently that's networking and some file system access
  options.

src/Preference.h

@@ -8,11 +8,28 @@
 #include "RageUtil.h"
 class XNode;
 
+enum class PreferenceType
+{
+	// Allow reading and writing of the preference through Lua.
+	// This is the default behavior.
+	Mutable,
+
+	// Mark the preference as read-only i.e. don't allow setting of the 
+	// preference through Lua.
+	Immutable,
+
+	// The preference is deprecated.
+	// This deprecated flag will not be written to the Preferences file.
+	// If this preference was deprecated in favor of a new one, see
+	// TranslateDeprecatedFlags() to see the what it was deprecated in favor of.
+	Deprecated,
+};
+
 struct lua_State;
 class IPreference
 {
 public:
-	IPreference( const RString& sName );
+	IPreference( const RString& sName, PreferenceType type );
 	virtual ~IPreference();
 	void ReadFrom( const XNode* pNode, bool bIsStatic );
 	void WriteTo( XNode* pNode ) const;
@@ -36,10 +53,11 @@ public:
 	static void ReadAllDefaultsFromNode( const XNode* pNode );
 
 	RString GetName() { return m_sName; }
-	void SetStatic( bool b ) { m_bIsStatic = b; }
+	bool IsImmutable() { return m_bImmutable; }
 private:
 	RString	m_sName;
-	bool m_bIsStatic;	// loaded from Static.ini?  If so, don't write to Preferences.ini
+	bool m_bDoNotWrite;
+	bool m_bImmutable;
 };
 
 void BroadcastPreferenceChanged( const RString& sPreferenceName );
@@ -48,8 +66,8 @@ template <class T>
 class Preference : public IPreference
 {
 public:
-	Preference( const RString& sName, const T& defaultValue, void (pfnValidate)(T& val) = nullptr ):
-		IPreference( sName ),
+	Preference( const RString& sName, const T& defaultValue, void (pfnValidate)(T& val) = nullptr, PreferenceType type = PreferenceType::Mutable ):
+		IPreference( sName, type ),
 		m_currentValue( defaultValue ),
 		m_defaultValue( defaultValue ),
 		m_pfnValidate( pfnValidate )
@@ -131,14 +149,14 @@ public:
 	typedef Preference<T> PreferenceT;
 	vector<PreferenceT*> m_v;
 	
-	Preference1D( void pfn(size_t i, RString &sNameOut, T &defaultValueOut ), size_t N )
+	Preference1D( void pfn(size_t i, RString &sNameOut, T &defaultValueOut ), size_t N, PreferenceType type = PreferenceType::Mutable )
 	{
 		for( size_t i=0; i<N; ++i )
 		{
 			RString sName;
 			T defaultValue;
 			pfn( i, sName, defaultValue );
-			m_v.push_back( new Preference<T>(sName, defaultValue) );
+			m_v.push_back( new Preference<T>(sName, defaultValue, nullptr, type) );
 		}
 	}