OilCommand lexer mode

[andychu]

This is nice stuff that can't be fit in lex_mode_e.ShCommand for compatibility

In Commands:

• multiline strings like '''
• C strings like c'\n' instead of $'\n'
• redirects like &2 > &1 (parse_amp)
• eliminate here docs, use << 'string' instead
• $/ d+ / inline eggex
  • /// multiline eggex?

Things to disable:

• [[
• ((

Word Language:

• maybe: $(( )) ? in favor of $[ ]
• most of ${} except new stuff
• backticks: could use these for something else (then this becomes a parsing issue, not lexing)

[andychu]

It seems like we no longer need this, yay!