[Groff] several macro packages for grog

[Bernd Warken]

Suppose you have a file meintro.me with the `me' macro package
and pic.ms with the `ms' macro package.  It is not possible to use
both files at the same time for `groff'.  Providing the double option
`-me -ms'  will not work as well.

But `grog meintro.me pic.ms'  produces `groff -pte -me meintro.me pic.ms',
which is wrong because the `-me' is not right.

To fix this there are several methods in the case of several macro packages:

1) `grog' shall always produce right output in any case.  So it should
write several `-m' options.  The user has the task to handle this output.

2) `grog' exits with an error, but no error message is written.

3) `grog' exits with an error, and an error message is written.

In each case, I can provide a patch.  Please tell me which method you prefer.

Bernd Warken