LazUtils:  RefCountedObject, handle nested RleaseRef

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@43861 4005530d-fff6-0310-9dd1-cebe43e6787f
FPDebug: refactor circular references

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@43862 4005530d-fff6-0310-9dd1-cebe43e6787f