LazReport: check variable existence before trying to show it's composition (variables editor form), from Michel Tournay, issue 26281

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@45370 4005530d-fff6-0310-9dd1-cebe43e6787f
LazReport, implements Zoom in/out using CTRL+MouseWheel, from Michel Tournay, issue 26280

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@45371 4005530d-fff6-0310-9dd1-cebe43e6787f