verify: report first bad changeset
- add linkrev and file arguments to err
- track lowest reported linkrev in err
- find linkrev in a couple cases
- sort linkrevs when reporting a bunch of errors against a file
- tidy up lots of messages
- make more robust against damaged indexes
- report first bad changeset if an error is encountered
adding da/foo
adding foo
% manifest
200 Script output follows
drwxr-xr-x da
-rw-r--r-- 4 foo
200 Script output follows
-rw-r--r-- 4 foo