Blender Compatibility Script? Is there a script which can correct all compatibility breaks, (automatically looks what version of Blender the file was made with and adds whatever necessary to get it look like before)?

Example: Let's say normal map strength is now 10 times smaller. For files created prior to 2.67, just multiply the value with 10 after opening in a 2.67+ version, to get the effect the artist really created.

If not, is there a text file listing all those compatibility breaks so that we can understand why, when a file looks weird/wrong?
No, not as far as I know of.

Blender can load older files into newer Blender version, taking care of updating settings.

It's possible to write a script that changes the settings of a .blend file of course, but this would most likely be a workaround for problems in Blender's own conversion, so if there is really a bug there, it should be reported.

In other cases changes cant be easily converted since the settings are not 1:1 equivalent, so in those cases you probably have to accept some manual tweaking to get comparable settings.