Added support for hex strings to mysqlimport

A lot of new tests to mysqltest
Fixed bug with BDB tables and autocommit

mysql-test/t/comments.test

@@ -0,0 +1,17 @@
+#
+# Testing of comments
+#
+
+select 1+2/*hello*/+3;
+select 1 /* long
+multi line comment */;
+!$1065 /* empty query */;
+select 1 /*!32301 +1 */;
+select 1 /*!52301 +1 */;
+select 1--1;
+# Note that the following returns 4 while it should return 2
+# This is because the mysqld server doesn't parse -- comments
+select 1 --2
++1;
+select 1 # The rest of the row will be ignored
+;