ongoing work on StatusListner support

test case for StatusListner support 

Fixed synchronization problems. The iterator() method has been removed from 
the StatusManager interface. It has been replaced by getCopyOfStatusList
which, as the name indicates, returns a copy of the statusList contained in
the StatusManager instance. This avoids concurrency problems encountered
when the developer forget to synchronize on the statusManager before iterating
on its status list. 

Added a listener interface to status manager as suggested in LBCLASSIC-59 
by Anton Tagunov. 

Support for status listeners in Joran is still missing.

  host CPU

  under the target directory. See also http://www.qos.ch/pipermail/logback-dev/2008-July/002610.html
- logback now depends on slf4j version 5.1.3-snapshot
- lb-examples depends on slf4j-ext

- Related to LBCORE-32

  added support for passing the configuration file as a system property.
  The system property name is "logback.configurationFile". Values can be 
  of type URL, a file, or a resource name.

  I am guessing that this modification should satisfy the requirements
  for most users who voted on this issue. I am not too keen on adding
  other config directives as system properties as suggested by M. Fowles.

- apparently [1] if the test method starts with test, surefire will consider the test as junit 3.8 and will
  not call any methods annotated with @Before. Sigh.

[1] http://mail-archives.apache.org/mod_mbox/maven-users/200705.mbox/%3C394431.64158.qm@web83608.mail.sp1.yahoo.com%3E

- This is a modified and hopefully improved version of Raph Goer's patch.

  MDCLevelFilter was renamed as DynamicThresholdFilter.
  
  In particular, the syntax for configuring a DynamicThresholdFilter
  is much shorter and convenient than previously. Here is an example:.
  
	<turboFilter class="ch.qos.logback.classic.turbo.DynamicThresholdFilter">
		<Key>userId</Key>
		<DefaultThreshold>ERROR</DefaultThreshold>
		<MDCValueLevelPair>
			<value>user1</value>
			<level>INFO</level>
		</MDCValueLevelPair>
		<MDCValueLevelPair>
			<value>user2</value>
			<level>TRACE</level>
		</MDCValueLevelPair>

	</turboFilter>

  See also turboDynamicThreshold.xml.

  However, I am not 100% satisfied with the semantics of
  DynamicThresholdFilter. Expect it to change according to
  feedback received on the mailing lists.

- added support for "valueOf" convention.
 Joran now assumes that any class which has a static
 valueOf method taking a String as an argument can
 be built from a string. 
 
 Level, Duration and FileSize classes follow this convention.
 
 This patch is indirectly related to LBCLASSIC-53

  hopefully clearer.
- Joran now support complex types without the need to declare their class
  in the XML element, if the complex type can be instantiated unequivocally.
  This can make config files shorter.

No commit message

- added link to Lilith

Escaping is implemented selectively. Cerated a new interface called EscapeUtil.
In particular, FileNamePattern now uses AlmostAsIsEscapeUtil.

See also http://jira.qos.ch/browse/LBCLASSIC-56