Bug 26: pquery not getting removed from parameter list

In e.g. MultiPostDisplay, if generate() raises a NotFound exception because there are no posts in the result, it never gets to return a dict and thus pquery never gets set to None in the parameter list. Possible solutions: 1. alter the system to use a non-conflicting name for each query. 2. do something to ensure that changes to the parameter list get made even if there is a NotFound exception. 3. stop using NotFound exceptions and designate a special return value or something for the condition of a missing page.