* 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
* Added various views and helper functions used by the mining
computation but which may be re-used in other parts.
* Added mining computation update type and associated update function
* New constants: game.resources.weightBase (the value used to compute
weights from mining settings) and game.resources.extraction (the
quantity extracted in a day from a full provider at difficulty 0)
