adds walkthrough videos to source tree
adding links to the videos
Fix video links
html5 tags
better tutorials slugs
best-practices slugs updated
bp tutorials dir
bp tutorials toc
guide video
bp tutorials sidebar bug
Make all videos inline and fix links

As per Vicky.
Fix one last tutorial link.
Add webm version of videos.

ffmpeg 2.1.3 -c:v libvpx -crf 10 -b:v 3M

Roughly match original bitrate.  Smaller, slightly lower quality, but
they look reasonable.
adds explanation for converting macshapa to datavyu
trivial
also trivial
resolving errors I can't believe I missed
tutorials mess in api
Merge branch 'master' of https://github.com/databrary/docs-datavyu

Conflicts:
	source/api/tutorial/convert-macshapa-to-datavyu.txt
	source/api/tutorials/convert-macshapa-to-datavyu.txt
	source/guide/tutorial/convert-macshapa-to-datavyu.txt
Fix remaining /api/tutorials/ refs