Mining settings

* 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.

legacyworlds-server-data/db-structure/tests/user/040-functions/040-empire/010-create-empire.sql

@@ -0,0 +1,14 @@
+/*
+ * Test privileges on emp.create_empire()
+ */
+BEGIN;
+
+	SELECT plan( 1 );
+	
+	SELECT diag_test_name( 'emp.create_empire() - Privileges' );
+	SELECT throws_ok( $$
+			SELECT emp.create_empire( 1 , 1 , 200.0 )
+		$$ , 42501 );
+	
+	SELECT * FROM finish( );
+ROLLBACK;