Merge branch 'hv/coding-guidelines'

Merge branch 'hv/coding-guidelines'

In earlier days, "imitate the style in the neibouring code" was
sufficient to keep the coherent style, but over time some parts of
the codebase have drifted enough to make it ineffective.

* hv/coding-guidelines:
  Documentation/CodingGuidelines: spell out more shell guidelines