[Groff] changing *.man into *.<number>n and *.n into *.<number>

[Bernd Warken]

We have an unlucky usage for writing man-page names as `*.man'
without mentioning the man-page section.  That makes most
man-page sources in groff unreasonable

I propose to use change this naming scheme `*.man' into
`*.<number>n' and `*.n' into `*.<number>'.

Examples:
Both files `groff.man' as `groff.1n' and `groff.7n' as source
and as `groff.1' and `groff.7' after compiling.

A lot of work for implementing that within automake seems to be
necessary, so maybe a later time could be better.  If large
manual renaming is necessary, I could do that.

Bernd Warken