(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/subsidy_type.h

@@ -0,0 +1,22 @@
+/* $Id$ */
+
+/** @file subsidy_type.h basic types related to subsidies */
+
+#ifndef SUBSIDY_TYPE_H
+#define SUBSIDY_TYPE_H
+
+#include "core/enum_type.hpp"
+
+enum PartOfSubsidy {
+	POS_NONE =     0,
+	POS_SRC = 1 << 0, ///< bit 0 set -> town/industry is source of subsidised path
+	POS_DST = 1 << 1, ///< bit 1 set -> town/industry is destination of subsidised path
+};
+typedef SimpleTinyEnumT<PartOfSubsidy, byte> PartOfSubsidyByte;
+
+DECLARE_ENUM_AS_BIT_SET(PartOfSubsidy);
+
+typedef uint16 SubsidyID; ///< ID of a subsidy
+struct Subsidy;
+
+#endif /* SUBSIDY_TYPE_H */