Integrate shells into the the main file

[robrobinbin]

An empty PowerPoint file is already quite big on itself, so why not add some of the functionality of the shells to the main template file, for extra convenience.

I'm thinking about small overlay controls on the presentation, including one to switch to presenter mode. This way our presentation is truly standalone and started with just one click.

Some of the size increase could be compensated by adding a minified version too.

[paulrouget]

We want to keep things simple. It's not about the size, it's about the complexity. This bare template is good enough in many case, I don't think we want to add anything more to it.