Fixes LBCLASSIC-49

The getLogger() method in LoggerContext class will now throw an
IllegalArgumentException when invoked with a null argument.
  

- fixed LBCORE-21, 

  TimeBasedRollingPolicy will now check at initialization time
  to see if an existing target file needs to be rolled over
  
- further refactoring of TimebasedRollingPolicyTest

The writer field in WriterAppender has been marked as private, as suggested by Anders Hammar in LBCORE-34

Making BasicStatusManager more sub-class friendly

Added a setter for the StatusManager.

- copyright notices

- documentation on status listeners

- added copyright notice

Setting a message size limit of 256K.

LevelToSyslogSeverity.convert method did not cover the TRACE level.

This should make the code a somewhat clearer

In StackTracementElement proxy, the setPackageInfo method was renamed as 
setClassPackagingData for consistency. 

The steAsString field marked as transient to save a few byte during serialization
(we can reconstruct this field from 'ste')

- added an entry about logger deserialization (related to LBCLASSIC-74 )

Make ch.qos.logback.classic.Logger instances deserialize with a valid LoggerContext reference.
This is accomplished by the readResolve() method which returns a Logger
generated by org.slf4j.LoggerFactory which may or not be using the correct LoggerContext. However,
that is probably the best we can do at that stage.

Associated test case.

Fixed LBCORE-43

Properties can be read from a resource as well as file or "key/value" pairs.

On application which do not put data in the MDC, the CopyOnInheriteThreadLocal would
throw a NullPointerException.

Given dependencies on test-jar logback could not be build as 'mvn package' from 
a pristine local repository. One had to 'mvn install' first. 

- Added blurb on LBCORE-32 
- various updates to news.html

- In DynamicThresholdFilter, renamed the OnMatch as OnHigherOrEquals, 
  and OnMismatch as OnLower, while the new names may not be perfect, 
  I think they are better than the old ones.
  
- updated javadocs
- added copyright notice