unclear rules for opening/closing files

[Matt Dewar]

open/close for files was deferred to the user in commit c85def8. However, rule is unclear/violated in the following functions:

• read_to_sarr
• write_from_pipe
• write_to_display

Either need to replace open/close with check_open and check_rw, or add a handle_file branch/argument to handle if the file should be opened/closed.