Reviewed-by: ppedrot

Ack-by: JasonGross
Reviewed-by: herbelin
Reviewed-by: jashug
Reviewed-by: jfehrle
Reviewed-by: ppedrot

We also get rid of ploc.ml, now useless, relying a priori on more
robust code in lStream.ml for location reporting (see
e.g. parse_parsable in grammar.ml).

Reviewed-by: SkySkimmer

Reviewed-by: mattam82
Ack-by: Zimmi48

Reviewed-by: ejgallego

Docutils 0.17 creates problem with our Sphinx rtd theme.

Now that the platform takes care of it.