* configure.ac: Remove check for groff, add check for xmlto.

* configure.ac: Remove check for groff, add check for xmlto.
* Makefile: Add support for building man pages from DocBook XML refentry's
using xmlto.

* frontends/yasm/yasm.xml: New.  Source XML file for yasm(1) man page.
* frontends/yasm/yasm.1: Generated yasm(1) man page.  We may want to remove
this at some point, but it would have impact on those keeping up with HEAD.

* frontends/yasm/Makefile.inc: Add new yasm(1) man page to distribution and
install.

* HACKING: Update required tools list.  Rename "CVS" to "Subversion".
Remove "Generating ChangeLogs" section, as with Subversion this is not
necessary.

svn path=/trunk/yasm/; revision=1138