Documentation migration

Created by: cor3ntin

I'm in the process of moving some of the documentation from https://www.thymio.org/en:start to github and readthedocs. My initial goal was to use markdown but I'm reconsidering that choice and will use reStructuredText instead, which will work best for documenting APIs especially since there are some maths formulas. The process is unfortunately not automatic - at least not full and there is a lot of clean up to do, both because formatting issue and outdated content.

I suggest we keep the "outdated" information where they are and focus on what's relevant to 1.6+. We should spread the efforts over several weeks or months since it's quite tedious and there are more pressing matters. I think I will focus on the language/apis first since there are no questions regarding the content and move from there.

Added by @stephanemagnenat: As pointed out by @cor3ntin, we need to come with a structure for the documentation to be put on readthedocs. Here is what I propose:

Aseba

• About: brief overview of Aseba's history and concepts, content of https://www.thymio.org/en:start and https://www.thymio.org/en:asebaconcepts, also an explanation that each target has a different programming interface (see section targets)
• Getting started: an updated version of https://www.thymio.org/en:gettingstarted, later challenge is to be incorporated into playground.
• Studio, the text programming environment, content of https://www.thymio.org/en:asebastudio, https://www.thymio.org/en:asebastudioplot and https://www.thymio.org/en:thymioflash
• Playground, the robot simulator, general introduction to playground, partial content of https://www.thymio.org/en:thymiosimulation and https://www.thymio.org/en:asebaplayground
• Switch, a combination of new information for the new switch, https://www.thymio.org/en:asebaswitchremap and https://www.thymio.org/en:asebamedulla
• Command line tools, a description of the existing command line tools
• The language, content of http://aseba.readthedocs.io/en/latest/aseba-language.html
• Native functions standard library, content of http://aseba.readthedocs.io/en/latest/aseba-std-natives.html

Targets

• Thymio, documentation of the launcher, the firmware upgrader and network configurator tools, and content of http://aseba.readthedocs.io/en/latest/thymio-api.html
• E-puck, to be written
• Elisa 3, to ask Gilles

Not all these need to be added at once, but we should agree on the structure as soon as possible.