- Organize the rules in sections and subsections.
- Add some text about the linear git history (this can be seen as coding
style after all).
- Add comment coding style and non-public API documentation sections.
- A bit of section reordering.
- Move the configuration files info from HACKING into CODING_STYLE.md,
and make a new "Helping tools" section.
- Improve a bit the intro by adding a link to GNU's coding style. Also
coding style is not a matter of taste, this is the whole point which
is that once specified, it doesn't matter anymore if we prefer one
style or another.
- Replace the table of content with [TOC] macro. No need to maintain
this manually (it will only break with time).
- "Line width" section was wrongly indented.
Jehan