ludent does not handle comment blocks

Nobody has claimed this yet.

Sample to check:

``` sh
$ ( printf '--[[\n if a then\n if a then\n if a then\n ]]--' ; cat ludent ) | ./ludent |head
lua: ./ludent:133: 3
stack traceback:
[C]: in function 'assert'
./ludent:133: in function 'indent'
./ludent:137: in main chunk
[C]: in ?
--[[
if a then
if a then
if a then
]]--#!/usr/bin/env lua

string.count = function(str, s2)
local count = 0
for i = 1, #str do
if str:sub(i,i) == s2 then
```

Start by running the sample command in the issue and inspect ludent around lines 133-137, where the failure occurs. Trace how the indenter handles the nested Lua comment block and verify that the sample completes without the assertion error while preserving the expected indentation.

Written by the indexing model from the issue text.