In all programs, make -v return immediately with exit status 0 to

In all programs, make -v return immediately with exit status 0 to
be compliant with the GNU standard.

* src/devices/grodvi/dvi.cc (main),
src/devices/grohtml2/post-html.cc (main),
src/devices/grolbp/lbp.cc (main), src/devices/grolj4/lj4.cc
(main), src/devices/grops/ps.cc (main), src/devices/grotty/tty.cc
(main) src/preproc/eqn/main.cc (main), src/preproc/grn/main.cc
(main), src/preproc/html2/pre-html.cc (main),
src/preproc/pic/main.cc (main), src/preproc/refer/refer.cc (main),
src/preproc/soelim/soelim.cc (main), src/preproc/tbl/main.cc
(main), src/roff/groff/groff.cc (main), src/roff/troff/input.cc
(main): Implement it.
* NEWS: Updated.

* src/roff/groff/groff.cc (main): Add copyright notice.  Add refer
and postprocessors to the -v option.

* src/roff/grog/grog.pl: Implement -v.
* src/roff/grog/Makefile.sub (grog): Use @VERSION@.
* src/roff/grog/grog.man, doc/groff.texinfo: Updated.

* src/roff/nroff/nroff.sh: Implement -v.
* src/roff/nroff/Makefile.sub (nroff): Use @VERSION@.
* src/roff/nroff/nroff.man: Updated.

* src/preproc/eqn/main.cc (main): Fix comment typo.

* MORE.STUFF: Added info about djgpp port of grap.