Enabled 'include' and 'extends' to be able to use a file relative to the root path.

Enabled 'include' and 'extends' to be able to use a file relative to the root path, which is given as a compiler option.


Example (from the test case):

    extends /auxiliary/layout
    
    block content
        include /auxiliary/include-from-root

And that's how you pass the rootpath, if you know what I mean.

    jade.compile(str, { filename: path, pretty: true, rootpath: 'test/cases' });

This will help with cases like `include ../../../../../layout`