(svn r2921) -Codechange: moved all AI-code to 1 central place (ai/ai.c)

-Fix: removed the ability for the oldAI to cheat (this will criple him somewhat)
-Add: base-code for many improvements to come in the AI-system
-Add: added base-code for multiplayer AIs (DOES NOT WORK YET!)

ai/ai.h

@@ -0,0 +1,78 @@
+#ifndef AI_H
+#define AI_H
+
+#include "../functions.h"
+
+/* How DoCommands look like for an AI */
+typedef struct AICommand {
+	uint32 tile;
+	uint32 p1;
+	uint32 p2;
+	uint32 procc;
+
+	uint32 dp[20];
+
+	struct AICommand *next;
+} AICommand;
+
+/* The struct for an AIScript Player */
+typedef struct AIPlayer {
+	bool active;            //! Is this AI active?
+	AICommand *queue;       //! The commands that he has in his queue
+	AICommand *queue_tail;  //! The tail of this queue
+} AIPlayer;
+
+/* The struct to keep some data about the AI in general */
+typedef struct AIStruct {
+	/* General */
+	bool enabled;           //! Is AI enabled?
+	uint tick;              //! The current tick (something like _frame_counter, only for AIs)
+
+	/* For network-clients (a OpenTTD client who acts as an AI connected to a server) */
+	bool network_client;    //! Are we a network_client?
+	uint8 network_player;   //! The current network player we are connected as
+} AIStruct;
+
+VARDEF AIStruct _ai;
+VARDEF AIPlayer _ai_player[MAX_PLAYERS];
+
+// ai.c
+void AI_StartNewAI(byte player);
+void AI_PlayerDied(byte player);
+void AI_RunGameLoop(void);
+void AI_Initialize(void);
+void AI_Uninitialize(void);
+int32 AI_DoCommand(uint tile, uint32 p1, uint32 p2, uint32 flags, uint procc);
+
+#define AI_CHANCE16(a,b)    ((uint16)     AI_Random()  <= (uint16)((65536 * a) / b))
+#define AI_CHANCE16R(a,b,r) ((uint16)(r = AI_Random()) <= (uint16)((65536 * a) / b))
+
+/**
+ * The random-function that should be used by ALL AIs.
+ */
+static inline uint AI_RandomRange(uint max)
+{
+	/* We pick RandomRange if we are in SP (so when saved, we do the same over and over)
+	 *   but we pick InteractiveRandomRange if we are a network_server or network-client.
+	 */
+	if (_networking)
+		return InteractiveRandomRange(max);
+	else
+		return RandomRange(max);
+}
+
+/**
+ * The random-function that should be used by ALL AIs.
+ */
+static inline uint32 AI_Random(void)
+{
+/* We pick RandomRange if we are in SP (so when saved, we do the same over and over)
+	 *   but we pick InteractiveRandomRange if we are a network_server or network-client.
+	 */
+	if (_networking)
+		return InteractiveRandom();
+	else
+		return Random();
+}
+
+#endif /* AI_H */