New search feature, merge fixes from CivicJobs

Added a new type of search to the Paginated controller.  An invertible,
boolean search that will add or remove a single SQL clause component
to/from the query based on the presence or lack of a certain GET
variable.

Allows me to have a toggle on the search for News which turns off the
default date limiting (last 30 days).

Will be eventually merged into Events, and then expanded upon (perhaps
split into a different search type) for per year searches as well.

Also merged in main.php and request.php changes/fixes from CivicJobs
that enable fallback routes to receive arguments and form links
properly.

In preparation for using this code as a baseline for CivicJobs, I split
the configuration of the paginated results/searches/etc. out from the
main controller itself, hence the addition of
incphp/paginated_config.php.