Fix for nested partials indenting.
Fix for nested partials indenting.

Fixes #167
sophatvathana/mustache.php,irontec/mustache,evdevgit/mustache.php,bobthecow/mustache.php,ericariyanto/mustache.php,zuluf/mustache.php,thecocce/mustache.php,BrunoDeBarros/mustache.php,cgvarela/mustache.php