Add docblock indent fixer

Ensure that docblocks for class methods and attributes are indented if present
EDIT: Ensure that any docblock uses the same indentation as the documented subject, regardless the type
I suspect this can be done differently with [strrchr](http://php.net/manual/en/function.strrchr.php) (see example 1). Because it involves no type conversion between string and array, it might be the case that's actually faster. Some benchmarking is needed to confirm this. 

One way or the other, converting strings to array should be a last resort, IMO.