Request for language support: Factor

Hello, and thanks for your continued work on highlight!

This is a request for Factor language highlighting support. The associated file extension: .factor.

Some existing lexers:

• Pygments.
• Rouge
• Sublime Text (includes a more thorough sample than included in this issue directly)

---

FWIW here's a small code sample:

USING: io kernel math.functions math.parser ranges sequences ;
IN: fizzy

MAIN: [
  100 [1..b] [
    dup [ 3 divisor? ] [ 5 divisor? ] bi 2dup or [
      [ drop ] 2dip
      [ "Fizz" "" ? ] [ "Buzz" "" ? ] bi* append
    ] [ 2drop number>string ] if
    print
  ] each
]

And here's how pygments highlights it, via rich-cli: