- fix possible memory leaks in ProjectAddTreeNode

git-svn-id: https://svn.code.sf.net/p/codeblocks/code/trunk@9610 2a5c6006-c6dd-42ca-98ab-0921f2732cef
- compiler: Use nullptr instead of 0L

git-svn-id: https://svn.code.sf.net/p/codeblocks/code/trunk@9611 2a5c6006-c6dd-42ca-98ab-0921f2732cef