Changes needed to the file_info structure

[Luke Kenneth Casson Leighton]

> Please also keep in mind that the current client code is going to be
> scrapped. Luke has already done it, in fact, it is just that we
> haven't properly propogated the changes the the main tree. 

i'm trying to persuade jeremy that we need to move to BRANCH_NTDOM's
client code, but i am leaving the actual decisions on what to take from
BRANCH_NTDOM up to him.