function isInRange(pos, start, end) {
      if (typeof pos != 'number') {
        // Assume it is a cursor position. Get the line number.
        pos = pos.line;
      }
      if (start instanceof Array) {
        return inArray(pos, start);
      } else {
        if (end) {
          return (pos >= start && pos <= end);
        } else {
          return pos == start;
        }
      }
    }
Check if pos is in the specified range, INCLUSIVE.
Range can be specified with 1 or 2 arguments.
If the first range argument is an array, treat it as an array of line
numbers. Match pos against any of the lines.
If the first range argument is a number,
  if there is only 1 range argument, check if pos has the same line
      number
  if there are 2 range arguments, then check if pos is in between the two
      range arguments.