Do not flatten content to do not mutate multiline strings

s = "line1
   line2
      line3"

differs from

s = "line1
line2
line3"
Algorithm of token analyzing changed

Now we iterate through tokens (instead of lines). To create a line
we need to find new line token. If it is found we can process this
this line in old way.
Versioning expected output

It will be possible to see what wrong or changed
If you have added new test to example.rb, simply override expected
file with command:

 $ruby ../bin/ruby-beautify < example.rb > example_beautified.rb

and commit changes. With diff you have a difference
Tests for already indented blocks and multi-line strings
Proper formatting of multi-line strings with interpolation
Corrected variable name
version bump.