* Add an AbstractTraceEntryWithStackTrace that includes stack trace handling.
* Add a selector macro/template combo to conveniently select the right base
class depending on whether stack traces are enabled or not.
* Minor style cleanups.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@43045 a95241bf-73f2-0310-859d-f6bbb57e9c96