[GRASS5] v.out.dxf: small updates -> useless + tip

[tlaronde at polynum.org]

Hello,

I have sent a message announcing that I wanted to make some small updates
to v.out.dxf. Reason: the resulting dxf was puzzling users with a blank page
and I wanted/needed to be able to automatically display "something" when
launching a program, zooming on the data.

After investigation (some may already know but if not this may be of some
use to others):

- when the file have texts, the programs generally zoom on the data; when
there are no, the whole extend is displayed from $INSBASE to east most.
- specifying $PLIMMIN and $PLIMMAX could do the trick but these exist not
in DXF R10.

As a result, this is probably not the trouble to change just that.

BTW, could still the backup and OLD sections be removed if there are believed
to be useless, reducing the size of the code to look at?

TIA.