(svn r1323) Adding autoreplace feature

This feature works much like autorenew, but it will get you a new engine type instead of a new one of the same type. Once 
ordered, it will automatically replace the engines while they visits a depot. The GUI for setting this up have been added on the 
vehicle overview windows
Note: autorenew is now autoreplace, but to the same engine type
Nice new features, that was added to make this possible
- windows can now have two independant vertical scrollbars
- CMD_SHOW_NO_ERROR have been added as a flag for DoCommandP. It will make it do the action instead of showing the red box with 
estimated costs even if shift is pressed
- fixed problem where enginetypes where not initialized when loading a game. It's now done in InitializeGame()

command.h

@@ -149,7 +149,7 @@ enum {
 	CMD_GIVE_MONEY = 112,
 	CMD_CHANGE_PATCH_SETTING = 113,
 
-	CMD_RENEW_VEHICLE = 114,
+	CMD_REPLACE_VEHICLE = 114,
 };
 
 enum {
@@ -172,6 +172,7 @@ enum {
 	CMD_NO_WATER = 0x400,
 	CMD_NETWORK_COMMAND = 0x800,		// execute the command without sending it on the network
 	CMD_NO_TEST_IF_IN_NETWORK = 0x1000, // When enabled, the command will bypass the no-DC_EXEC round if in network
+	CMD_SHOW_NO_ERROR = 0x2000,
 };
 
 //#define return_cmd_error(errcode) do { _error_message=(errcode); return CMD_ERROR; } while(0)