* Fixed privileges on both variants of defs.uoc_natural_resource()
* Added user unit tests which check execution privileges on all (new)
stored procedures and INSERT/UPDATE/SELECT/DELETE privileges on all
(new) tables
* Added structures for resource definitions, natural resources
definitions, resource providers, empire resources and empire mining
settings (both empire-wide and planet-specific).
* Added a few common utility functions to the SQL test suite. These
functions allow test initialisation to be a little shorter.
* Added "MINE" production type and an associated building definition.
The production will not be added to the XML dump or to the output of the
planets summary page, as this is extremely temporary.
