(svn r9315) -Merge: The newhouses branch. With this merge comes almost complete support for

the newhouses grf specs, so all newhouses grfs will be playable in the game.

Many thanks to everyone who contributed code and ideas, and all the testers
who found things we missed.

src/newgrf_callbacks.h

@@ -37,10 +37,42 @@ enum CallbackID {
 
 	CBID_TRAIN_ARTIC_ENGINE         = 0x16,
 
+	/* Called (if appropriate bit in callback mask is set) to determine whether
+	 * the house can be built on the specified tile. */
+	CBID_HOUSE_ALLOW_CONSTRUCTION   = 0x17,
+
 	CBID_VEHICLE_CARGO_SUFFIX       = 0x19,
 
+	/* Called (if appropriate bit in callback mask is set) to determine
+	 * the next animation frame. */
+	CBID_HOUSE_ANIMATION_NEXT_FRAME = 0x1A,
+
+	/* Called (if appropriate bit in callback mask is set) for periodically
+	 * starting or stopping the animation. */
+	CBID_HOUSE_ANIMATION_START_STOP = 0x1B,
+
+	/* Called (if appropriate bit in callback mask is set) whenever the
+	 * construction state of a house changes. */
+	CBID_CONSTRUCTION_STATE_CHANGE  = 0x1C,
+
 	CBID_TRAIN_ALLOW_WAGON_ATTACH   = 0x1D,
 
+	/* Called (if appropriate bit in callback mask is set) to determine the
+	 * colour of a town building. */
+	CBID_BUILDING_COLOUR            = 0x1E,
+
+	/* Called (if appropriate bit in callback mask is set) to decide how much
+	 * cargo a town building can accept. */
+	CBID_HOUSE_CARGO_ACCEPTANCE     = 0x1F, // not yet implemented
+
+	/* Called (if appropriate bit in callback mask is set) to indicate
+	 * how long the current animation frame should last. */
+	CBID_HOUSE_ANIMATION_SPEED      = 0x20,
+
+	/* Called (if appropriate bit in callback mask is set) periodically to
+	 * determine if a house should be destroyed. */
+	CBID_HOUSE_DESTRUCTION          = 0x21,
+
 	/* This callback is called from vehicle purchase lists. It returns a value to be
 	 * used as a custom string ID in the 0xD000 range. */
 	CBID_VEHICLE_ADDITIONAL_TEXT    = 0x23,
@@ -48,16 +80,28 @@ enum CallbackID {
 	/* Called when building a station to customize the tile layout */
 	CBID_STATION_TILE_LAYOUT        = 0x24,
 
+	/* Called (if appropriate bit in callback mask is set) to determine which
+	 * cargoes a town building should accept. */
+	CBID_HOUSE_ACCEPT_CARGO         = 0x2A, // not yet implemented
+
 	/* Called to determine if a specific colour map should be used for a vehicle
 	 * instead of the default livery */
 	CBID_VEHICLE_COLOUR_MAPPING     = 0x2D,
 
+	/* Called (if appropriate bit in callback mask is set) to determine how much
+	 * cargo a town building produces. */
+	CBID_HOUSE_PRODUCE_CARGO        = 0x2E, // not yet implemented
+
 	/* Called when the player (or AI) tries to start or stop a vehicle. Mainly
 	 * used for preventing a vehicle from leaving the depot. */
 	CBID_VEHICLE_START_STOP_CHECK   = 0x31,
 
 	/* Called to play a special sound effect */
 	CBID_VEHICLE_SOUND_EFFECT       = 0x33,
+
+	/* Called (if appropriate bit in callback mask set) to determine whether a
+	 * town building can be destroyed. */
+	CBID_HOUSE_DENY_DESTRUCTION     = 0x143,
 };
 
 /**
@@ -83,6 +127,23 @@ enum StationCallbackMask {
 	CBM_CUSTOM_LAYOUT = 1, ///< Use callback to select a tile layout to use
 };
 
+/**
+ * Callback masks for houses.
+ */
+enum HouseCallbackMask {
+	CBM_HOUSE_ALLOW_CONSTRUCTION  = 0,
+	CBM_ANIMATION_NEXT_FRAME      = 1,
+	CBM_ANIMATION_START_STOP      = 2,
+	CBM_CONSTRUCTION_STATE_CHANGE = 3,
+	CBM_BUILDING_COLOUR           = 4,
+	CBM_CARGO_ACCEPTANCE          = 5,
+	CBM_ANIMATION_SPEED           = 6,
+	CBM_HOUSE_DESTRUCTION         = 7,
+	CBM_HOUSE_ACCEPT_CARGO        = 8,
+	CBM_HOUSE_PRODUCE_CARGO       = 9,
+	CBM_HOUSE_DENY_DESTRUCTION    = 10,
+};
+
 /**
  * Result of a failed callback.
  */