(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()

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static const byte _dir_to_straight_trackdir[4] = {

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	0, 1, 8, 9,

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};

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static const byte _reverse_dir[4] = {

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//	3, 0, 1, 2

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	2, 3, 0, 1

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};