Fixed #3: mutex is unlocked before deleting its parent
Merge pull request #4 from alorence/ea3970980625f996908e052aa742b69f7c0b64ca

Fix issue #3: unlock mutex before deleting its parent
Modification to default console appender output format
Made slight changes to the documentation
Qt4: use "qDebug" as function name for handled Qt messages
Fixed three spelling errors.