Reentrancy resilience
Implement multi thread activitylogger output for .net 4.5 and 4.0. Add some test.
Add a unit test to test some arguments null on the output
Fix bugged implementation and add test to show it works
Add generic method to centralize Interlocked pattern, minor change to tests
Change reentrancy to know if exception come from multi or mono thread

 - Fix implementation to detect reentracy cross all the activity logger method
 - Fix Activity logger to be resilient to internal reentracy
 - Fix ActivityLogger Output, Morph<> method now accept null as a morpher's possible value
Minor rewriting.

- Added Debug.Assert.
- Defined text Resources for errors.
Stronger test for multi-threaded reentrancy.
Merge pull request #6 from Invenietis/f-multithread-activitylogger

Activity logger reentrancy resilience and output multithread support