bitbake/logging: Overhaul internal logging process

At the moment it bugs me a lot that we only have one effective logging
level for bitbake, despite the logging module having provision to do
more advanced things. This patch:

* Changes the core log level to the lowest level we have messages of
  (DEBUG-2) so messages always flow through the core logger
* Allows build.py's task logging code to log all the output regardless
  of what output is on the console and sets this so log files now
  always contain debug level messages even if these don't appear
  on the console
* Moves the verbose/debug/debug-domains code to be a UI side setting
* Adds a filter to the UI to only print the user requested output.

The result is more complete logfiles on disk but the usual output to the
console.

There are some behaviour changes intentionally made by this patch:

a) the -v option now controls whether output is tee'd to the console.

Ultimately, we likely want to output a message to the user about where the
log file is and avoid placing output directly onto the console for every
executing task.

b) The functions get_debug_levels, the debug_levels variable, the
set_debug_levels, the set_verbosity and set_debug_domains functions are
removed from bb.msg.

c) The "logging" init function changes format.

d) All messages get fired to all handlers all the time leading to an
increase in inter-process traffic. This could likely be hacked around
short term with a function for a UI to only request events greater than
level X. Longer term, having masks for event handlers would be better.

e) logger.getEffectiveLevel() is no longer a reliable guide to what
will/won't get logged so for now we look at the default log levels instead.

[YOCTO #304]

(Bitbake rev: 45aad2f9647df14bcfa5e755b57e1ddab377939a)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/bin/bitbake

@@ -190,7 +190,7 @@ Default BBFILES are the .bb files in the current directory.""")
     # server is daemonized this logfile will be truncated.
     cooker_logfile = os.path.join(os.getcwd(), "cooker.log")
 
-    bb.utils.init_logger(bb.msg, configuration.verbose, configuration.debug,
+    bb.msg.init_msgconfig(configuration.verbose, configuration.debug,
                          configuration.debug_domains)
 
     # Ensure logging messages get sent to the UI as events
@@ -228,6 +228,7 @@ Default BBFILES are the .bb files in the current directory.""")
     try:
         return server.launchUI(ui_main, server_connection.connection, server_connection.events)
     finally:
+        bb.event.ui_queue = []
         server_connection.terminate()
 
     return 1

bitbake/bin/bitdoc

@@ -430,9 +430,8 @@ Create a set of html pages (documentation) for a bitbake.conf....
                        action = "store_true", dest = "verbose", default = False )
 
     options, args = parser.parse_args( sys.argv )
-
-    if options.debug:
-        bb.msg.set_debug_level(options.debug)
+ 
+    bb.msg.init_msgconfig(options.verbose, options.debug)
 
     return options.config, options.output