Work towards adding support for VS2010 and Neon to the build-svn-deps-win.pl script.

You can specify which version of Subversion you're building deps for via the
SVN_VER variable (e.g. SVN_VER=1.7.x).

NEON can be enabled to download/build if SVN_VER is older than 1.8 or NEON=1 is
set.

* tools/dev/build-svn-deps-win.pl
  (VCUPGRADE, PYTHON, NEON_VER, NEON_URL, PROJREF_URL, NEON_FILE, PROJREF_FILE,
   SVN_VER, NEON, SVN_VER): New variables.

  (set_svn_ver_defaults, check_vs_ver): New functions.

  (download_dependencies): Download python script that fixes project references
    and neon if configured to.

  (extract_dependencies): Extract neon if configured to.

  (upgrade_solution): Handle an interactive conversion where needed.

  (build_httpd): Use interactive conversion when building under VS2010, adjust
    workarounds to httpd build to be VS version dependent.

  (main): Check the Visual Studio Version.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1488798 13f79535-47bb-0310-9956-ffa450edef68