Query classifier ignored implicit commits in cases of write commands. Fixed it.

Added more tests for transaction support. Mostly different cases where some command triggers implicit commit in the middle of transaction.

server/modules/routing/readwritesplit/test/test_implicit_commit5.sql

@@ -0,0 +1,14 @@
+USE test;
+DROP PROCEDURE IF EXISTS simpleproc;
+SET autocommit=0;
+BEGIN;
+DELIMITER //
+CREATE PROCEDURE simpleproc (OUT param1 INT)
+BEGIN
+    SELECT COUNT(*) INTO param1 FROM t;
+END //
+DELIMITER ;
+SELECT (@@server_id) INTO @a;
+SELECT @a; --should read from slave
+DROP PROCEDURE IF EXISTS simpleproc;
+COMMIT;