GitLab

* Move reset() method to logger_manager (and _impl) and remove from the general
  logger classes.
* Correct problem whereby some messages went to stdout and some to stderr.
* Split the shell file testing into separate files, each testing one aspect of
  the logger.

Added the file appender, which routes output to a file (appending
to a file if one exists).

The root logger name is now obtained from the global variable
accessed by get/setRootLoggerName().

Also, the console appender now provides the correct pattern.

This is the global object that controls the logging system, so
it is logical that initialization is done here instead of in the
Logger class (which controls the operation of one logger).

Added basic logger manager and its implementation, plus an untested
console appender.  Also modified logger_support_test to use that
appender and have got part way through creating a file logger test.