Documentation refresh and issue #71

#### The Good:
1. Solved issue #71 - dyna doesn't crash anymore on syntax error in rules
2. Documentation is now available online and looks modern: https://dyna.readthedocs.org

I would be glad to add you as administrators on readthedocs.org project, and I will switch it to the main repo once this commit is merged.

#### The Bad:
I'm sorry, I'm new to git, so I've mixed things up here.
Most of changes are about updated the look and feel of the documentation. The text didn't change (except for the white-space in Dijkstra tutorial). 
Issue #71 is just one commit, d81a7819ea6cf6f944d9f947ff98e440fc14c69a, if you wish to keep only it.

#### The Ugly:
I've used [sphinx-bootstrap-theme](https://github.com/ryan-roemer/sphinx-bootstrap-theme) to refresh the look of the documentation. Probably it should have been referenced/included/imported from that git repo, not just copied.