feature-request / doc-actualization (right-margin)

[Werner]

page-formatting,
paper-block, vertical an horizontal spacing:

right-margin: if right margin is given, line-width is determined as paper-width
(from paper-size) minus left-margin minus right-margin.

If there is given right margin AND line-width, the last given argument should be
used. (Maybe a warning could be given out?)

At least NR should mention under Horizontal dimensions, that at the moment
right-margin has to be determined via paper-width - left-margin - line-width,
i.e. via line-width...