* 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)
* Added a system that allows "dirty" tests to be written. These tests
actually need to change the database, so a temporary test database must
be created to run them.
