Indentation of partials according to spec

Hi,

I noticed that the following testcase of the mustache spec is not rendered correctly (the partial is not indented):

  - name: Standalone Indentation
    desc: Each line of the partial should be indented before rendering.
    data: { content: "<\n->" }
    template: |
      \
       {{>partial}}
      /
    partials:
      partial: |
        |
        {{{content}}}
        |
    expected: |
      \
       |
       <
      ->
       |
      /

The current outcome is:

\
 |
<
->
|

/

I am using mustache templating for markdown templates where whitespace does matter, so this is a real problem for me.

I saw that the readme states Passes all of the mustache specification tests modulo whitespace differences. Is this on purpose or would a PR that tries to fix this difference from the spec be welcome?

Start by comparing the linked Mustache specification testcase with the current rendering behavior, using the issue's template and partial as the reproduction. The work is done when each line of the partial is indented as shown in the specification's expected output.