Database management changes

* Added in-base logging through a foreign data wrapper, which is only
possible using PostgreSQL 9.1
* Renamed database-related configuration files to indicate that they are
samples, and added the "real" names to the Git ignore list. Server
distribution modified accordingly.
* Removed PL/PgSQL registration (it was only necessary on 8.4)
* Added pgTAP SQL definitions and a script which will (hopefully) be
executed by the build system after the main Java build in order to
execute database unit tests. The script supports both admin- and user-
level testing. I also added a few tests to make sure the testing framework
actually runs them.
* Added documentation about the database definitions structure

legacyworlds-server-data/db-structure/tests/user/priv/sys/logs.sql

@@ -0,0 +1,39 @@
+BEGIN;
+	SELECT plan( 3 );
+
+	--
+	-- Insertion through sys.write_log()
+	--
+	CREATE OR REPLACE FUNCTION _test_this( )
+		RETURNS BIGINT
+	AS $$
+		SELECT sys.write_log( 'test' , 'WARNING'::log_level , 'test' );
+	$$ LANGUAGE SQL;
+	SELECT lives_ok( 'SELECT _test_this()' );
+	DROP FUNCTION _test_this( );
+
+	--
+	-- Direct insertion must fail
+	--
+	CREATE FUNCTION _test_this( )
+		RETURNS VOID
+	AS $$
+		INSERT INTO sys.logs( component , level , message )
+			VALUES ( 'test' , 'WARNING'::log_level , 'test' );
+	$$ LANGUAGE SQL;
+	SELECT throws_ok( 'SELECT _test_this()' , 42501 );
+	DROP FUNCTION _test_this( );
+
+	--
+	-- Updates must fail
+	--
+	CREATE OR REPLACE FUNCTION _test_this( )
+		RETURNS VOID
+	AS $$
+		UPDATE sys.logs SET component = 'random' WHERE component = 'test';
+	$$ LANGUAGE SQL;
+	SELECT throws_ok( 'SELECT _test_this()' , 42501 );
+	DROP FUNCTION _test_this( );
+	
+	SELECT * FROM finish( );
+ROLLBACK;