Convert README to Markdown

Move contributing file

Move CONTRIBUTING.md to project root

Grab latest changes

Small refactor of build server file uploads, and added extra check for 'already uploaded' assets to GitHub

Docs: fence filenames containing wildcards

Docs: Add Contributing doc

CONTRIBUTING.md: Where to find daily installers

Time-index conversion isues with Markers and Keyframes

Exponential zoom levels (and only 14 of them, instead of 800)

Fixing copyright to use translation-friendly formatting, and hiding hardware decode preference (for now)

There isn't actually an "Other Downloads" link on the referenced page anymore, so the previous description was confusing.

(The presence of the "Daily Installers" button on that download page is also confusing, as it does nothing and should probably go away. But that's an issue for the website, not the code.)

Converted from .github/CONTRIBUTING.md with pandoc

Update DPI for Inkscape titles from 90 to 96

Merge from origin master

Updated copyrights to say 2018 (instead of 2016).