* The quantities of resources extracted from mines will now be updated
as soon as they have a reason to. This includes planet assignment,
abandonment, ownership changes, and updates to mining priorities.
* The mining update will now remove the current resource income from the
providers, and only then re-compute all extracted quantities. This is
more logical and corresponds to the way the other game updates work.
* Fixed bug in extraction computation where the size of the planet's
happy population was used instead of the happy/total ratio when
adjusting the mining production for riots.
* The following SQL scripts must be re-executed to upgrade a database:
-> 040-functions/040-empire.sql
-> 040-functions/145-resource-providers.sql
-> 040-functions/147-empire-mining.sql
-> 050-updates/120-planet-mining.sql
* 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.
