(svn r17113) -Change [FS#265][FS#2094][FS#2589]: apply the subsidy when subsidy's destination is in station's catchment area and cargo packets originate from subsidy's source

-Change [FS#1134]: subsidies aren't bound to stations after awarding anymore, they still apply to town or industry, no matter what station is used for loading and unloading. Awarded subsidies from older savegames are lost
-Change [NoAI]: due to these changes, AISubsidy::GetSource and AISubsidy::GetDestination now return STATION_INVALID for awarded subsidies

src/industry.h

@@ -19,6 +19,7 @@
 #include "tile_type.h"
 #include "company_type.h"
 #include "strings_type.h"
+#include "subsidy_type.h"
 
 enum {
 	INVALID_INDUSTRY       = 0xFFFF,
@@ -125,6 +126,8 @@ struct Industry : IndustryPool::PoolItem<&_industry_pool> {
 	Year last_prod_year;                ///< last year of production
 	byte was_cargo_delivered;           ///< flag that indicate this has been the closest industry chosen for cargo delivery by a station. see DeliverGoodsToIndustry
 
+	PartOfSubsidyByte part_of_subsidy;  ///< NOSAVE: is this industry a source/destination of a subsidy?
+
 	OwnerByte founder;                  ///< Founder of the industry
 	Date construction_date;             ///< Date of the construction of the industry
 	uint8 construction_type;            ///< Way the industry was constructed (@see IndustryConstructionType)