Configurable logging

[Alan DeKok <aland@deployingradius.com>]

  I have just committed updates to the "linelog" module (including
documentation) that significantly increase it's usability.  The goal is
to move most of the hard-coded log messages to this module.  Once these
log messages are added to the configuration, the existing hard-coded
messages can be deleted.

  We're looking for volunteers to examine the existing log messages, and
to submit sample one-line log formats for the "linelog" module.

  Alan DeKok.