This patch prepares support for floating point samples (and probably
other formats). It changes the meaning of the "bits" attribute from a
bit count to a symbolic value.
After we've been hit by Large File Support problems several times in
the past week (which only occur on 32 bit platforms, which I don't
have), this is yet another attempt to fix the issue.
Don't call g_error(), which will abort the process and dump core.
This patch does not affect all the config_get_X() functions. These
need some more refactoring.