Add "Limit search to parents siblings" option

[xja]

The "Limit search to siblings of current search item" is very useful. It would be handy to be able to also include siblings of the parent of the search item as well, so that you could put the all of your Search items under a particular parent item (I often have many sibling search items) within a Folder linked to that parent item.

eg, in the case below, Search1, Search2, and Search3 would search all children (and their children) of Project A, as opposed to just children of Searches.

Project A
|
|-Searches
| |_Search1
| |_Search2
| |_Search3
|
|_Tasks
| |_Task1
| |_Task2
| |_Task3|
|
|_Mail
|
|_Contacts