Support automatic inclusion of files using ** (e.g. reference/**)

[GeertvanHorrik]

Fixes #48

Usage is fairly simple (in DocNet):

"Pages" : 
    {
        "Introduction" :
        {
            "Introduction" : "introduction/introduction.md"
                },
        "FAQ" : 
        {
            "General" : "faq/general.md",
            "MVVM" : "faq/mvvm.md",
            "Problem solving" : "faq/problem-solving.md",
            "Performance considerations" : "faq/performance-considerations.md",
        },
                "API reference" : "reference/**"
    }

The API reference part uses the ** at the end. It means that all (sub)folders inside /reference will be checked for MD files. A few automatic rules:

1. Auto index files will always be generated
2. The title of the md files will be retrieved from the actual MD files (so the first non-empty line will be used as title)

This becomes extremely useful when parts of the docs are generated via a tool such as SharpDox.

[FransBouma]

Could you write a couple of documentation lines to the docs in the gh-pages branch? Thanks :)

[GeertvanHorrik]

See #60

[FransBouma]

Due to the tabs vs. spaces whitespacing (code used tabs, you used spaces) git thinks the whole navigationlevel file has changed, which isn't the case. I can't see properly what has changed in the file to review it. Will try to revert spaces to tabs and then do a diff.

[GeertvanHorrik]

Sorry, didn't notice that. Probably the habit of hitting CTRL + K + D when editing lots of stuff in a file. Normally I try to accept the coding standard of the original project.

[FransBouma]

Merged!