Stuffpages

* fixed in PAGES sorting
* examples are now built into the `docs` directory and available as demo at https://fladd.github.io/StuffPages
* fixed a bug in examples

* Python 3 compatibility
* Properly installable with pip
* New `stuffpages` command
* New breadcrumb listing
* New syntax for pages listing (reverse sort, sort by any defaults/meta data)
* Build only pages that have actually changed
* New `_resource` directory for linked files and resources (default is global)
* Copy files with absolute links into unique directories in `_resources`
* Pages are not self-contained by default
* New `selfcontained` setting (to have local `_resources` directory for each page)
* No `index` setting needed anymore (`index.md` as filename suffices)
* New `html_head`, `html_nav`, `html_header`, `html_footer` sections in `config.py`
* New `nonav` setting
* Hacks to fix HTML errors from the markdown package, footnote position and permalink symbol position

* Added option to sort pages list by descriptions instead of titles
* New "Simple blog" example

- fixed a bug with page names in page listings
- files that include page listings are now always rebuilt during update

- added index pages (define `index` in `settings`)
- added page listing (`[PAGES]`)
- added hierarchical directory structures (default, switch off with `norecursion` in `settings`)
- only pages whose source changed since last build are built (time is saved in file `.lastupdate`)

- new `default.css` style
- new `simple.css` style
- new default extensions
- new examples
- permalinks for headings
- fixed nested code blocks
- fixed unicode bug