* tmac/doc-common (Ss): Add final `.ns' (similar to `.Sh') to

* tmac/doc-common (Ss): Add final `.ns' (similar to `.Sh') to
suppress additional whitespace after the header.

* tmac/doc-ditroff, tmac/doc-nroff (Am): New string to be in sync
with NetBSD.

* src/preproc/grn/grn.man, tmac/groff_mdoc.man, NEWS: Updated.

* tmac/doc-common(doc-volume-operating-system-ateol): New flag.
(Dt): Use it to improve language localization (especially Russian
and French).

* src/preproc/grn/gprint.h (BSPLINE, BEZIER): New macros.
* src/preproc/grn/hdb.cc (DBGetType): Parse spline and bezier
drawing commands.
* src/preproc/grn/hgraph.cc (drawwig): Add parameter to control
curve type.
Call `picurve' for BSPLINE.
(HGPrintElt): Handle BSPLINE.
* src/preproc/grn/README: Document it.