[Feature/Restore] grep

[The Grim Sleeper]

So rather then spend my time on something useful or desired by the community, like having ';' be the hotkey for radio-talk, I spend my time fixing up a neglected piece of turbo-nerdery for that aspect of the game nobody can be bothered with:

grep

the TermOS command for searching for text in other text!

Key features:

• Warnings when files can not be read.
  
• -s option to suppress those warnings.
  
• -i option for case insensitive searches.
  
• -o option for print_only_match (no idea what that is, thank you AIBM, your code still works)
  
• -r to search within folders.
  
• Not crashing the server when some fucking asshat makes a symbolic link inside a folder that targets a super of that folder and then running 'grep -r' on any folder in that hierarchy.
  

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• Compare
  
• Patch