Interface Editor, Method deletion : Fix AV caused by double object freeing

git-svn-id: http://svn.code.sf.net/p/lazarus-ccr/svn@3195 8e941d3f-bd1b-0410-a28a-d453659cc2b4
Method deletion : remove deleted item from the list

git-svn-id: http://svn.code.sf.net/p/lazarus-ccr/svn@3196 8e941d3f-bd1b-0410-a28a-d453659cc2b4