## Changes
- Print warnings and errors by default.
- Fix ErrAlreadyPrinted not to be logged at Error level.
- Format log messages as "Warn: message" instead of "WARN" to make it
more readable and in-line with the rest of the output.
- Only print attributes (pid, mutator, etc) and time when the overall
level is debug (so --debug output has not changed much).
## Tests
- Existing acceptance tests show how warning messages appear in various
test case.
- Added new test for `--debug` output.
- Add sort_lines.py helper to avoid dependency on 'sort' which is
locale-sensitive.
## Changes
- New test covering failures in reading .git. One case results in error,
some result in warning (not shown).
- New helper withdir runs commands in a subdirectory.
## Tests
New acceptance test.
Denis Bilenko