field does not work

Fix to prevent MyISAM from reading data from NULL BLOB.
Fix to make record comparison independent of values of unused bits in
record.
Updating binlog positions in tests.

into  romeo.(none):/home/bk/b22583-mysql-5.1-new-rpl

Post-merge fixes.

master info structure.

into  quant.(none):/ext/mysql/bkroot/mysql-5.1-new-rpl

into  mysql.com:/nfsdisk1/lars/bk/mysql-5.1-new-rpl

into  mysql.com:/home/bar/mysql-5.1-rpl

into  mysql.com:/home/bar/mysql-5.1-rpl

into  quant.(none):/ext/mysql/bkroot/mysql-5.0-rpl

into  quant.(none):/ext/mysql/bkroot/mysql-5.1-new-rpl

into  quant.(none):/ext/mysql/bkroot/mysql-5.0-rpl

into  quant.(none):/ext/mysql/bkroot/mysql-5.0-rpl

when merging into 5.1.

into  quant.(none):/ext/mysql/bk/mysql-5.0-rpl-warnings

Replacing local directory.

into  mysql.com:/nfsdisk1/lars/MERGE/mysql-5.1-merge

into  mysql.com:/nfsdisk1/lars/MERGE/mysql-5.0-merge

into  mysql.com:/home/bar/mysql-5.0.b24478

Bug N 15126 character_set_database is not replicated (LOAD DATA INFILE need it)
Positions of some binlog events were changed because of
additional logging of @@collation_database.

into  mysql.com:/home/bar/mysql-5.0.b15126

This patch fixes problem that LOAD DATA could use different
character sets when loading files on master and on slave sides:
- Adding replication of thd->variables.collation_database
- Adding optional character set clause into LOAD DATA

Note, the second way, with explicit CHARACTER SET clause
should be the recommended way to load data using an alternative
character set.
The old way, using "SET @@character_set_database=xxx" should be
gradually depricated.

into  mysql.com:/home/gluh/MySQL/Merge/5.1-opt

into  quant.(none):/ext/mysql/bk/mysql-5.0-bug25306

into  mysql.com:/home/psergey/mysql-5.1-bug26117

Before the fix: 
  ha_partition objects had ha_partition::m_part_info==NULL and that caused
  crash
After: 
- The new ha_partition::clone() function makes the clones use parent's
  m_part_info value.
- The parent ha_partition object remains responsible for deallocation of
  m_part_info.

into  quant.(none):/ext/mysql/bk/mysql-5.0-bug25306

into  mysql.com:/nfsdisk1/lars/MERGE/mysql-5.1-merge

into  mysql.com:/nfsdisk1/lars/MERGE/mysql-5.0-merge