Taking care of ob_* caching

It may happen that WordPress or Plugins mess up the output buffer (known as on_*-Functions).
We enhanced the use of WordPress-Functions by taking care of ob_level-irregularities.

• Bugfix: Content disappears when function are messing around with ob_*
• Bugfix: Do not render twice

0.1.1 WP_CONTENT_DIR Patch

• Fix: Wait for WP_CONTENT_DIR to be set

Add ".html.twig" lookup to WordPress templating

• Add ".html.twig" lookup to WordPress templating
• Allow actions to be used as Twig-Functions
• Allow filter to be used as Twig-Functions and Twig-Filter