Identifiers with embedded escape characters were not handled correctly by
  some SHOW statements due to some old code that was doing some extra unescaping.


mysql-test/r/show_check.result:
  Add new results
mysql-test/t/show_check.test:
  Add new regression test
sql/sql_parse.cc:
  Remove remove_escape() -- it is not actually necessary, and now harmful because
  identifiers may include escape characters.