IDE: messages: add filter: cancel

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@45385 4005530d-fff6-0310-9dd1-cebe43e6787f
lazbuild: nicer error message

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@45386 4005530d-fff6-0310-9dd1-cebe43e6787f