- Bump versions and revert XML migration of the release documents in

- Bump versions and revert XML migration of the release documents in
  releng/9.1 branch.  The doc tree release/9.1.0 for this release still uses
  SGML toolchain[1].

- Add SVNROOT{BASE,SRC,DOC,PORTS} for subversion repository URLs and
  BRANCH{SRC,DOC,PORTS} for the branches to generate-release.sh, and
  remove -p, -r, -d options.  The revision to be built should be specified
  in the URL.

- Add {WORLD,KERNEL}_FLAGS to generate-release.sh.  These were supported in
  the old release build framework.

- Disable to use binary package for docproj port during a release build.
  This package should be built successfully.

Pointy hat to:	hrs [1]
Approved by:	re (implicitly)

git-svn-id: svn://svn.freebsd.org/base/releng/9.1@243705 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f