Added support for hex strings to mysqlimport

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

mysql-test/r/key_diff.result

@@ -0,0 +1,39 @@
+a	b	a	b
+A	B	A	B
+b	A	A	B
+C	c	A	B
+D	E	A	B
+a	a	A	B
+A	B	b	A
+b	A	b	A
+C	c	b	A
+D	E	b	A
+a	a	b	A
+A	B	C	c
+b	A	C	c
+C	c	C	c
+D	E	C	c
+a	a	C	c
+A	B	D	E
+b	A	D	E
+C	c	D	E
+D	E	D	E
+a	a	D	E
+A	B	a	a
+b	A	a	a
+C	c	a	a
+D	E	a	a
+a	a	a	a
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t1	ALL	a	NULL	NULL	NULL	5	
+t2	ALL	b	NULL	NULL	NULL	5	where used
+a	b	a	b
+A	B	b	A
+a	a	b	A
+A	B	a	a
+a	a	a	a
+b	A	A	B
+C	c	C	c
+a	b
+A	B
+a	a