FPDebug: refactor

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@43276 4005530d-fff6-0310-9dd1-cebe43e6787f
FPDebug: tests

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@43277 4005530d-fff6-0310-9dd1-cebe43e6787f