Plans for rewriting perlopentut

• Mention where the reference documentation is so readers know where to get a fuller picture of what open can do beyond what the tutorial presents.
• Consider discussing STDIN and family as special constants, rather than bringing in the concept of bareword filehandles.
• Add a mention of DATA, which is currently missing.
• Describe better when it is safe to use 2-arg open, but encourage the use of 3-arg open by default.
• Explain when explicit close and checking it's return value is important.
• Add a section on specifying encoding in a more prominent location, including use of :raw for binary files.
• Use Getopt::Long for short options as well as long.
• Mention writing to a string: open my $fh, '>', $str.
• Remove opening sockets and named pipes, which are already covered in perlipc, and aren't suitable for a tutorial. Consider moving file locking elsewhere.
• ...?