Publish documentation on readthedocs

[nicoddemus]

• Extract documentation from docstrings and publish on readthedocs;
• Add proper install and usage instructions;
• Craft a minimal complete example of the usage;
• Fix documentation build;
• Check and update examples;
• Investigate a better layout for the "reference" section;
• Improve in auto generated documentation;
• Extent example list with ... (we should list more advanced features and create a item for each one);

Suggestion for new items are welcome.