Added support of converion specifiers mentioned in manual but missing in code.


mysql-test/r/date_formats.result:
  Added tests of str_to_date() with new %T, %r and %V, %v conversion specifiers, and also 
  some other specifiers for which tests were missing previously.
mysql-test/t/date_formats.test:
  Added tests of str_to_date() and new %T, %r and %V, %v conversion specifiers, and also 
  some other specifiers for which tests were missing previously.
sql/item_timefunc.cc:
  Added support for %T, %r, %V, %v, %X, %x conversion specifiers to extract_date_time()
  function. Also simplified a bit calculation of dates from week number.