FILE_DELETE don't complain when file is existant ...

[alaingdl]

a detail, but FILE_DELETE, 'toto.titi' when file 'toto.titi' does not exist should complain

IDL> FILE_DELETE, 'toto.titi'
% FILE_DELETE: Unable to delete file. File: toto.titi
  No such file or directory
% Execution halted at: $MAIN$          

[alaingdl]

many options and messages are missing in FILE_DELETE.

no fully tested and not didicated test in the testsuite.

can be tricky because we need to manage wildcards (* and ?), complain is file name is '', ...