IDE: designer: check result of AddClicked

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@45048 4005530d-fff6-0310-9dd1-cebe43e6787f
IDE: designer: before adding a new component check for syntax errors, bug 20512

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@45049 4005530d-fff6-0310-9dd1-cebe43e6787f