* Modified mining settings stored procedures to use text identifiers
instead of numeric identifiers
* Added DAO for mining settings and controller for resource operations
* Added UpdateEmpireMiningSettingsCommand and associated command
delegate. The command always returns NullResponse.
* Overview page templates split into multiple files for clarity, added
priority update form to the empire economy view and associated web
server handler
* Changed the way mining settings work: use a priority value (between 0
and 4) as the weight. Leaving them as they were before would have caused
numerous problems (and a lot of unnecessary code to work around them)
* Empire mining settings will be created along with the empire's own
record. By default all natural resources will have weight = 2.
* Added a set of four stored procedures which can be used to update an
empire's mining settings, including planet-specific settings. The
emp.mset_update_start() function can be used to start an update (on an
empire's settings if there is only one parameter, or on a planet's
settings if there are two parameters); the emp.mset_update_set() and
emp.mset_update_apply() functions are then used to modify the settings
and apply the changes, respectively.
