Note skin, plumber build, source refactor, fixes

- Notes toggle using scribe commands
- New commands to collapse a single note and collapse all notes
- Separation of code into multiple sources
- Various fixes
- Implemented new styles for notes as a "skin" (src/skin/gu-noting.less):

![note-screenshot-2014-09-26](https://cloud.githubusercontent.com/assets/2298529/4418856/247466ee-4564-11e4-9208-e5d39986010d.png)

I know it's sill early but it would be good to have an explanation of why we need the start and end barriers and why we need to remove them etc.