Mining computation update

* 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)

legacyworlds-server-data/db-structure/tests/user/040-functions/145-resource-providers/030-get-extraction-factor.sql

@@ -0,0 +1,13 @@
+/*
+ * Test privileges on verse.get_extraction_factor()
+ */
+BEGIN;
+	SELECT plan( 1 );
+
+	SELECT diag_test_name( 'verse.get_extraction_factor() - Privileges' );
+	SELECT throws_ok( $$
+		SELECT verse.get_extraction_factor( 0.5 , 0.5 )
+	$$ , 42501 );
+	
+	SELECT * FROM finish( );
+ROLLBACK;