NO_BACKSLASH_ESCAPES was not heeded in LOAD DATA INFILE
and SELECT INTO OUTFILE.  It is now.

mysql-test/r/loaddata.result:
  Show that SQL-mode NO_BACKSLASH_ESCAPES is heeded in
  INFILE/OUTFILE, and that dump/restore cycles work!
mysql-test/t/loaddata.test:
  Show that SQL-mode NO_BACKSLASH_ESCAPES is heeded in
  INFILE/OUTFILE, and that dump/restore cycles work!
sql/sql_class.cc:
  Add function to enquire whether ESCAPED BY was given.
  When doing SELECT...OUTFILE, use ESCAPED BY if specifically
  given; otherwise use sensible default value depending on
  SQL-mode features NO_BACKSLASH_ESCAPES.
sql/sql_class.h:
  Add function to enquire whether ESCAPED BY was given.
sql/sql_load.cc:
  When doing LOAD DATA INFILE, use ESCAPED BY if specifically
  given; otherwise use sensible default value depending on
  SQL-mode features NO_BACKSLASH_ESCAPES.