Adding thorough tests covering what happens with escaped sequences

in the SQL parser.

Various backslash escapes and quote-quote escaped sequences are covered
in combination with single and multi-byte characters.

This is especially important for the character sets that can have 0x5C
as the second byte in a multi-byte character (big5, cp932, gbk, sjis).

swe7 is also a special character set, because in swe7 0x5C is used for
both escape character and for "LATIN CAPITAL LETTER O WITH DIAERESIS".

mysql-test/include/bytes2.inc

@@ -0,0 +1,21 @@
+#
+# Create a table with all 2 byte sequence values
+#
+
+--source include/bytes.inc
+
+CREATE TABLE halfs (a BINARY(1));
+# "bytes" is a temporary table, hence is not allowed in joins
+# Create a non-temporary copy.
+INSERT INTO halfs SELECT * FROM bytes;
+CREATE TEMPORARY TABLE bytes2 (
+  a BINARY(2),
+  hi BINARY(1),
+  lo BINARY(1),
+  KEY(a),
+  KEY(lo)
+) ENGINE=MyISAM;
+INSERT INTO bytes2
+SELECT CONCAT(t1.a, t2.a), t1.a, t2.a FROM halfs t1, halfs t2
+ORDER BY t1.a, t2.a;
+DROP TABLE halfs;