More updates

 * Better jump-to-file.
 * Fix list formatting.
 * Better syntax highlighting.
 * Updated README with explanation.
 * Added `example.txt` file.
Add todo list items

 O prefix for un-done items
 X prefix for done items
Fix highlighting of blockquotes

 * They weren't require to be anchored to the start of the line.
Improve day snippet
Added folding

based on http://vimcasts.org/episodes/writing-a-custom-fold-expression/
Allow '/' in sub-section header