(svn r5999) -Feature: change the original date format to a 32 bits format based at the year 0.

The game date subsystem now allows someone to start in the year 0 and continue
up to the year 5 000 000. However, you currently cannot build anything before 
1920 as there is no newgrf support for dates before 1920 or after 2090 yet.

network.h

@@ -89,7 +89,7 @@ typedef struct NetworkGameInfo {
 typedef struct NetworkPlayerInfo {
 	char company_name[NETWORK_NAME_LENGTH];					// Company name
 	char password[NETWORK_PASSWORD_LENGTH];					// The password for the player
-	byte inaugurated_year;													// What year the company started in
+	Year inaugurated_year;													// What year the company started in
 	int64 company_value;														// The company value
 	int64 money;																		// The amount of money the company has
 	int64 income;																		// How much did the company earned last year