dLeyna components allow information to be output using a logging mechanism.
This service currently implements 2 output mechanisms and different 'levels' of
importance for messages.

Logging type:
-------------

dLeyna components can choose between 'syslog' or glib logging system.

The logging type can be set at configuration time and changed dynamically at
runtime.

When configuring the project, use the --with-log-type option to select your
desired logging service.

	--with-log-type=0: syslog service will be used.
	--with-log-type=1: glib system will be used.


The logging options of a dLeyna service can also be modified at runtime
by modifying the service's configuration file. Each dLeyna service has
its own configuration file, e.g., dleyna-server.conf or dleyna-renderer.conf,
and these files are located in the default local configuration folder (usually
in your home folder, /home/<user>/.config/).

Each configuration file has an option called log-type.

	log-type=0: syslog service will be used.
	log-type=1: glib system will be used.

dLeyna components monitor these configuration files.  Any changes on it are
applied immediately.


Logging level:
--------------

The logging level selects which kind of messages in the code are going to be
logged.

The logging level is set at configuration time and a subset of this initial
configuration can be changed dynamically at run time.

dLeyna components define 6 levels of importance:

	1: errors
	2: critical messages
	3: warnings
	4: messages/notices
	5: informational messages
	6: debug messages

When configuring the project, use the --with-log-level option to select your
desired logging messages.

Allowed values for --with-log-level are:
	0 = disabled
	7 = default (=1,2,5)
	8 = all (=1,2,3,4,5,6)
	1,..,6 = a comma separated list of log level

ex: --with-log-level=2,5,6 will log only critical, informational and debug
messages.

The service can also be changed at runtime by modifying the configuration file.
The service's configuration file has an option called log-level.
The values for log-level are the same as for --with-log-level.

Be careful, logging messages not selected during the configuration of the
project, could not be enabled at runtime.  These messages are stripped at
compilation time.  You can only specify a sub selection of the one defined with
--with-log-level option.

ex:
--with-log-level=2,5,6
At run time you can change log-level to
log-level=2: Only critical messages will be logged.
log-level=5,6: sub selection of --with-log-level.
log-level=8: enable all options define by --with-log-level. Same as =2,5,6
log-level=0: disable logging

DOES NOT WORK: log-level=1,3. Not part of --with-log-level option.


Macros:
-------

To log messages, use the predefined macros below:

DLEYNA_LOG_LEVEL_ERROR
DLEYNA_LOG_LEVEL_CRITICAL
DLEYNA_LOG_LEVEL_WARNING
DLEYNA_LOG_LEVEL_MESSAGE
DLEYNA_LOG_LEVEL_INFO
DLEYNA_LOG_LEVEL_DEBUG

DLEYNA_LOG_LEVEL_ERROR should not be used in release code but only for debug
purpose.
When log-level=1 (error message) is used with log-type=1 (glib), a call to
the the logging function is always fatal, and results in a call to abort().
This is not acceptable in release.