RLisp code formatter

Just after the highlighter, here's another important piece of language infrastructure - code formatter. For now it only re-adjusts amount of indentation. It doesn't move )s around, change other whitespace, or modify any code.

Here's an example. Before:

(defmacro cmd options
(let hash_index -1)
[options each_with_index &(fn (x i)
(cond
(and [hash_index == -1] [x is_a? Symbol] [[x to_s] =~ /:\Z/]) (set! hash_index i)
(and [hash_index == -1] [x == '=>]) (set! hash_index [i - 1]))
)]
(if (== hash_index -1)
(sendq options)
(do
(let normal_args [options get [0 ... hash_index]])
(let hash_args [options get [hash_index .. -1]])
`(sendq ,@normal_args (hash ,@hash_args))))
)

After:

(defmacro cmd options
  (let hash_index -1)
  [options each_with_index &(fn (x i)
    (cond
      (and [hash_index == -1] [x is_a? Symbol] [[x to_s] =~ /:\Z/]) (set! hash_index i)
      (and [hash_index == -1] [x == '=>]) (set! hash_index [i - 1]))
  )]
  (if (== hash_index -1)
    (sendq options)
    (do
      (let normal_args [options get [0 ... hash_index]])
      (let hash_args [options get [hash_index .. -1]])
      `(sendq ,@normal_args (hash ,@hash_args))))
)