Add "fail if unknown" and "mark if unknown" flags to object header messages.
This gives the library a clean way to tell older libraries that a message should
not be just ignored if it's unknown, but that other actions should occur.
Tested on:
Mac OS X/32 10.4.9 (amazon)
FreeBSD/32 6.2 (duty)
FreeBSD/64 6.2 (liberty)
Linux/32 2.6 (chicago)
Linux/64 2.6 (chicago2)
Bug fix
Description:
Currently, when the library encounters an object header message that isn't
know, it fails to open that object in the file.
Solution:
Allow the library to skip over the unknown object header message and
continue to process the remaining messages, in the hope that the skipped
message isn't important later. If it is important, it will be caught at
a higher level of the library.
Platforms tested:
FreeBSD 4.7 (sleipnir)
