has changed since 4.0.14'
We need to calculate cost of RANGE
scan if it is present instead of cost of 
FULL scan.


mysql-test/r/order_by.result:
  more accurate row estimation
  for RANGE scan
mysql-test/r/range.result:
  added test case for bug #1724
  'WHERE ... IN() optimizer behaviour has changed since 4.0.14'
mysql-test/r/select.result:
  please ignore
mysql-test/t/range.test:
  added test case for bug #1724
  'WHERE ... IN() optimizer behaviour has changed since 4.0.14'
sql/sql_select.cc:
  fix for bug #1724 'WHERE ... IN() optimizer behaviour 
  has changed since 4.0.14'
  We need to calculate cost of RANGE
  scan instead of cost of FULL scan
  if RANGE is present
  Few comments cleaned up.