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 a
assuming destination a-hg
initializing destination a-hg repository
scanning source...
sorting...
converting...
4 a
3 b
2 c
1 d
0 e
pulling from ../a
searching for changes
no changes found