Update shortcode doc for 0.13-DEV

Update of the doc to reflect the shortcode  implemention in HEAD.
Added a new command `hugo list drafts` and `hugo list future`
Move template library into it's own package (tpl). No longer dependent on hugolib. Can be used externally.
refactor handlers to use types instead of structs.
fixed #656. Templates work properly when watching.
typo: practical
fix version command so that it will work with all supported config formats and added tests
Added stou.dk to showcases
Added link to my blogpost about travelling with Hugo in asia
Correct path in theme search order
Added makefile that builds with git information

I have put the extra linker flags in a makefile to avoid having to remember the long command to get the commitHash in the version command.

See comment by tatsushid here:
https://github.com/spf13/hugo/issues/540

NB: only tested on Mac OS x 10.10.1 since that is what I have access to
fixing race condition in CreatePages
Enable descriptive header IDs.

Enable blackfriday.EXTENSION_AUTO_HEADER_IDS to generate the name of the
header ID from the text in the header. Works for prefix and underline
headers.

- TOC extraction had to be modified to look for `<li><a href="#`>
  instead of `#toc_` because of this change.
- Fixed a number of tests that depended on the presence of `toc_` with
  as an `id` or as a `href` value.
- Renames the earlier parameter `footnoteref` to `documentId` as it more
  accurately represents the nature of the parameter. The `documentId` is
  appended to all generated headers through the new HTML renderer
  parameter `HeaderIDSuffix`.
update summary.md with info on handling of html tags
Add markdownify template filter

Note that this is a Markdownify filter, and is named as such; it's not a Asccidoc filter or in any way connected to a Page.

Fixes #524
Doc for markdownify

This small function feels important enough to maybe deserve more than these three lines, but this will have to do for now.

This assumes that #652 gets merged.
adding appvoyer support for Windows CI integration
Adding Prev/Next functionality to all lists of pages (sections, taxonomies, etc)