Fix headers

Hi,

This fixes an issue with the raw headers attribute not being updated when calling *$page->setRawHeaders($rawHeaders)* and another one, where the *$page->getHeaders()* does not return the headers from the *$this->rawHeaders* attribute if *$page->setRawHeaders($rawHeaders)* is not called.

The branch also has another change in the base layout that I did some time ago to be able to override just some parts instead of the whole template. Please let me know if want me to revert this change, although I find it useful.

Cheers,
Stan