IDE: free handlers in component palette, fixes a memory leak

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41879 4005530d-fff6-0310-9dd1-cebe43e6787f
IDE: use TreeView also for flat component list. Allows use of one FilterEdit for all views. Improve interaction with comp palette.

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41880 4005530d-fff6-0310-9dd1-cebe43e6787f