Desktop app (Windows)

Lots of people are asking for an offline version, which we should eventually support. I've always wanted to make a slick Metro app, perhaps this could be it.

Even though it's offline, I think we should figure out a good way to integrate with #55 so an offline copy of their notebook is always available, and any changes made while online sync back to the notebook, and any changes made while offline sync back as soon as they come back online.

Start by reading issue #55 and the repository's existing application structure to determine how notebooks are represented and whether a desktop entry point exists. Done would mean a Windows offline app with local notebook availability and synchronization of online and offline changes, but the issue provides no implementation files or tests.

Written by the indexing model from the issue text.