difference between timestamp in values of months and quarters.)

Problem:  when requesting timestamp diff in months or quarters, it
would only examine the date (and not the time) for the comparison.

Solution:  increased precision of comparison.


mysql-test/r/func_time.result:
  Additional test results
mysql-test/t/func_time.test:
  Additional tests
sql/item_timefunc.cc:
  Fix for timestamp diff issue.  Added microsecond precision when
  comparing months or quarters; previously only examined date for
  these comparisons.