Complete revision [v2.0]

- Huge rewrite and simplification of all templates
- New blueprints
- New search
- Introduced tags instead of categories
- Simpler results
- Minor design adjustments
- Typography overview page
- More basic styles including Markdown Extra features
- Dropped all "old IE" clutter
- Cleaned up and rearranged the entire CSS
- Added Kirby Core and Panel as submodules