Import patch suggested at BUG: 233

Thanks to Christian Lampe for report and proposed patch
Merge branch 'release'
Cleanup CFind output
Add new option to gdcm::Trace

Adding functionality to write directly to a file based on a filename
this should help for wrapped language
Merge branch 'release'
Fix doxygen generation
Remove non-existing dir
Merge branch 'release'
Document new option
Merge branch 'release'
Activate the __FUNCTION__ helper
Rework internals of gdcm::Trace to be more flexible

This change allows one to register only debug, warning and/or error stream outputs
Merge branch 'release'

Conflicts:
	CMake/gdcmPlatformCxxTests.cmake
Add new cmake option to preserver gdcm::Trace macro messages
Solve two remaining issues with hidden compilation flags on gcc
Remove two simple warnings
Merge branch 'release'

Conflicts:
	Source/Common/CMakeLists.txt
Update gdcmData to the latest
Adding new private attributes
Update gdcmData to the latest