Fixes broken links, code blocks and other things that
`sphinx-build docs/source docs/out -E` complained about.
Signed-off-by: Michael Grupp <grupp@magazino.eu>
This restructures the doc as a tutorial leading newcomers to becoming experimented users.
It adds pages on:
- how to get started with Cartographer on a new .bag
- how Cartographer works and can be tuned step-by-step
- how to use "extra" features of Cartographer
- how to contribute to Cartographer
It also provides some cosmethic changes with: new titles, non-indented code blocks, various illustrations, reworked paragraphs for clarity...