(svn r15027) -Merge: tomatos and bananas left to be, here is NoAI for all to see.

NoAI is an API (a framework) to build your own AIs in. See:
   http://wiki.openttd.org/wiki/index.php/AI:Main_Page
 With many thanks to:
  - glx and Rubidium for their syncing, feedback and hard work
  - Yexo for his feedback, patches, and AIs which tested the system very deep
  - Morloth for his feedback and patches
  - TJIP for hosting a challenge which kept NoAI on track
  - All AI authors for testing our AI API, and all other people who helped in one way or another
-Remove: all old AIs and their cheats/hacks

src/ai/api/ai_subsidy.cpp

@@ -0,0 +1,94 @@
+/* $Id$ */
+
+/** @file ai_subsidy.cpp Implementation of AISubsidy. */
+
+#include "ai_subsidy.hpp"
+#include "ai_error.hpp"
+#include "ai_company.hpp"
+#include "ai_date.hpp"
+#include "../../openttd.h"
+#include "../../economy_func.h"
+#include "../../station_base.h"
+#include "../../cargotype.h"
+
+/* static */ bool AISubsidy::IsValidSubsidy(SubsidyID subsidy_id)
+{
+	return subsidy_id < lengthof(_subsidies) && _subsidies[subsidy_id].cargo_type != CT_INVALID;
+}
+
+/* static */ bool AISubsidy::IsAwarded(SubsidyID subsidy_id)
+{
+	if (!IsValidSubsidy(subsidy_id)) return false;
+
+	return _subsidies[subsidy_id].age >= 12;
+}
+
+/* static */ AICompany::CompanyID AISubsidy::GetAwardedTo(SubsidyID subsidy_id)
+{
+	if (!IsAwarded(subsidy_id)) return AICompany::INVALID_COMPANY;
+
+	return (AICompany::CompanyID)((byte)GetStation(_subsidies[subsidy_id].from)->owner);
+}
+
+/* static */ int32 AISubsidy::GetExpireDate(SubsidyID subsidy_id)
+{
+	if (!IsValidSubsidy(subsidy_id)) return -1;
+
+	int year = AIDate::GetYear(AIDate::GetCurrentDate());
+	int month = AIDate::GetMonth(AIDate::GetCurrentDate());
+
+	if (IsAwarded(subsidy_id)) {
+		month += 24 - _subsidies[subsidy_id].age;
+	} else {
+		month += 12 - _subsidies[subsidy_id].age;
+	}
+
+	year += (month - 1) / 12;
+	month = ((month - 1) % 12) + 1;
+
+	return AIDate::GetDate(year, month, 1);
+}
+
+/* static */ CargoID AISubsidy::GetCargoType(SubsidyID subsidy_id)
+{
+	if (!IsValidSubsidy(subsidy_id)) return CT_INVALID;
+
+	return _subsidies[subsidy_id].cargo_type;
+}
+
+/* static */ bool AISubsidy::SourceIsTown(SubsidyID subsidy_id)
+{
+	if (!IsValidSubsidy(subsidy_id) || IsAwarded(subsidy_id)) return false;
+
+	return GetCargo(GetCargoType(subsidy_id))->town_effect == TE_PASSENGERS ||
+	       GetCargo(GetCargoType(subsidy_id))->town_effect == TE_MAIL;
+}
+
+/* static */ int32 AISubsidy::GetSource(SubsidyID subsidy_id)
+{
+	if (!IsValidSubsidy(subsidy_id)) return INVALID_STATION;
+
+	return _subsidies[subsidy_id].from;
+}
+
+/* static */ bool AISubsidy::DestinationIsTown(SubsidyID subsidy_id)
+{
+	if (!IsValidSubsidy(subsidy_id) || IsAwarded(subsidy_id)) return false;
+
+	switch (GetCargo(GetCargoType(subsidy_id))->town_effect) {
+		case TE_PASSENGERS:
+		case TE_MAIL:
+		case TE_GOODS:
+		case TE_FOOD:
+			return true;
+		default:
+			return false;
+	}
+}
+
+/* static */ int32 AISubsidy::GetDestination(SubsidyID subsidy_id)
+{
+	if (!IsValidSubsidy(subsidy_id)) return INVALID_STATION;
+
+	return _subsidies[subsidy_id].to;
+}