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

% basic
% unknown
*** [alias] unknown: command bargle is unknown
% ambiguous
*** [alias] ambiguous: command s is ambiguous
% recursive
*** [alias] recursive: circular dependency on recursive
adding foo
% with opts
C foo