Implement connected node search

Create an interface for searching through connected networks of nodes.

These queries should be saved as nodes.

The "view" operation for these query nodes should execute the query and display the results.

Search options should include the following:

default starting node
follow parents
follow children
return a distinct set of node types (only the first of each node type found is returned)
search distance (how far from the starting node should be searched)
end points (don't search beyond these types of nodes, but include them in the results)
avoidance types (don't search these types of nodes at all, and don't include them in the results)
max results (do not search beyond this many results) **
search types (only return nodes that match these node types) **
search algorithm (Depth-first search, Breadth-first search, etc..) **

There should be a form on the search results page for specifying the node id (nid) of another node to start the search from. This value should override any default value that is specified.

Search algorithms should only follow nodes that are viewable by the current user. **

Provide a means of listing out available ("viewable" to current user) saved queries. This list should optionally be published as part of the a search form in the body of select node types.

Results should be paginated if possible.

(** these features are yet to be implemented, and all others are yet to be committed to CVS)