* autogen.sh: Use `gnulib-tool' to install gendocs.sh.
* Makefile.am (web-manual): New target. Builds a web manual using
gendocs.sh.
* configure.ac (AC_PREREQ): Require Autoconf 2.59 or later.
* autogen.sh: Workaround Automake requirement for NEWS and README.
We really should have them, but in practice we never had. This
ought not be considered a regression.