Fix LBCORE-78. 

AsynchronousCompressor shuts down the executor it created, thus avoiding a memory leak.

- cosmetic changes in Context

Removed 'synchronized' keyword from the incSize() and size() methods. 
Synchronization was causing a deadlock described in LBCLASSIC-81
These two methods are used internally by logback for testing purposes.

The getEffectiveLevel() method needs to be synchronized to protect
against concurrent modification when iterating over
childrenList.iterator().

  the collection returned by Collections.synchronizedList()

- preparing release 0.9.13
- minor doc changes

An NPE would be thrown when setting the level of a logger to null, if the
logger in question had children.

- removed slf4j-ext declaration from the parent pom. In child modules the slf4j-ext was being inserted in compile scope instead
  of test scope.
- updated documentation in relation to contextName and insertFromJNDI configuration directives. 

- migrated some tests to JUnit4 format
-  other cosmetic changes

Fixes LBCLASSIC-90. Logger reset set logger levels to NULL, except for the root logger which gets set to DEBUG.

  See also LBCLASSIC-43
- cosmetic changes

Added an FAQ entry:

  Is it possible for multiple JEE applications to share the same 
  configuration file but without stepping on each other's toes?


Related to LBCLASSIC-42

- converted all tests in logback-core to JUnit 4

I prefer
  try {
    r.lock();
    doSomething();
  } finally  {
    r.unlock();
  }
  
instead of 

  r.lock();
  try {
    doSomething();  
  } finally  {
    r.unlock();
  }

  because I think that the lock is held for a shorter time (however small it may be).
  In case r.lock() throws an exception, we are probably screwed in both approaches.

- relevant test cases

- logback now uses slf4j version 1.5.6
- ContextJNDISelector was refactored. The config file name for a new logger context is based on convention "logback-CONTEXTNAME.xml" 
  This obviates the need to set the "logback/configuration-resource" JNDI env-entry.

With each call to getLogger() method, LoggerContext will now retrieve the ILoggerFactory afresh from StaticLoggerBinder. 
This change enables context selectors of native implementations, e.g logback, to work correctly. 

  logback can succeed even in presence of recursive calls
  to LoggerFactory.getLogger (invoked during the initialization of
  logback). See also http://bugzilla.slf4j.org/show_bug.cgi?id=106
  and http://jira.qos.ch/browse/LBCORE-47
  
  This test fails if SLF4J 1.5.5 is used.
  
  Related to http://bugzilla.slf4j.org/show_bug.cgi?id=113
  and http://jira.qos.ch/browse/LBCORE-51

 - Absorb thrown SecurityException/AccessControlException when accessing system properties
   This fixes LBCLASSIC-86

instances running on multiple JVMs can safely write to the same log file. With 
certain limitations, prudent mode extends to RollingFileAppender. 

  from multiple JVM on different hosts