[Groff] need for mom checks in grog

[Bernd Warken]

Is mom intended to become a standard macro package in groff?  
If yes, then a suitable test must be provided in grog, otherwise
groffer will not be able to display mom files automatically.

Meanwhile, in all existing mom files, esp. in the mom example files 
there should be an explicit `.mso om.tmac'.

The new groffer-0.8 (released within the next 3 days) will also provide 
direct Postscript display, so `grog' should be worth being considered.

Bernd Warken