Add implementation of multi-aspect signalling and GRF support

Requires realistic braking

See: #247

src/newgrf.h

@@ -119,11 +119,13 @@ enum Action0RemapPropertyIds {
 	A0RPI_RAILTYPE_ENABLE_RESTRICTED_SIGNALS,
 	A0RPI_RAILTYPE_DISABLE_REALISTIC_BRAKING,
 	A0RPI_RAILTYPE_ENABLE_SIGNAL_RECOLOUR,
+	A0RPI_RAILTYPE_EXTRA_ASPECTS,
 	A0RPI_ROADTYPE_EXTRA_FLAGS,
 	A0RPI_GLOBALVAR_EXTRA_STATION_NAMES,
 	A0RPI_SIGNALS_ENABLE_PROGRAMMABLE_SIGNALS,
 	A0RPI_SIGNALS_ENABLE_RESTRICTED_SIGNALS,
 	A0RPI_SIGNALS_ENABLE_SIGNAL_RECOLOUR,
+	A0RPI_SIGNALS_EXTRA_ASPECTS,
 };
 
 enum GRFPropertyMapFallbackMode {
@@ -227,6 +229,10 @@ enum NewSignalCtrlFlags {
 	NSCF_RECOLOUR_ENABLED       = 3,                          ///< Recolour sprites enabled
 };
 
+enum {
+	NEW_SIGNALS_MAX_EXTRA_ASPECT = 6,
+};
+
 /** New signal control flags. */
 enum NewSignalAction3ID {
 	NSA3ID_CUSTOM_SIGNALS       = 0,                          ///< Action 3 ID for custom signal sprites
@@ -285,6 +291,7 @@ struct GRFFile : ZeroedMemoryAllocator {
 
 	const SpriteGroup *new_signals_group;    ///< New signals sprite group
 	byte new_signal_ctrl_flags;              ///< Ctrl flags for new signals
+	byte new_signal_extra_aspects;           ///< Number of extra aspects for new signals
 
 	GRFFile(const struct GRFConfig *config);
 	~GRFFile();