Allow (notimeout) cursor to be used outside of the initial jvm.

This means we need a way to create a DBCursor from a cursorId (plus other options like start/getnum), disable automatic cleanup (killing) of the cursorId (on finalize) and expose the cursor in a portable (serialized as a string?) way. Maybe it would be best to create a CursorBookmark object to encapsulate the information and so that a DBCursor can be constructed from it.

In some applications it may be more useful to do this rather than to construct a new query based on the current query parameters (copy + skip). The CursorBookmark could work in two ways potentially; one as a copy of the query (plus skip/position) or as a reference to the cursorId as described above. For this issue I will just address the second (cursorId) case.