Log Message:
Update subversion (and bindings) to 1.10.4.

 User-visible changes:
  - Minor new features and improvements:
    * Conflict resolver support for added vs unversioned file (r1845577)
    * Conflict resolver support for unversioned directories (r1846299)

  - Client-side bugfixes:
    * Fix: repos-to-WC copy with --parents doesn't create dirs (#4768)
    * Fix: foreign repo copy with peg/operative revisions (#4785)
    * Fix: foreign repo copy of file adding mergeinfo (#4792)
    * Fix: assertion failure using -rPREV on a working copy at r0 (#4532)
    * Fix: tree conflict message ends a sentence with a colon (#4717)

  - Server-side bugfixes:
    * Fix: unexpected SVN_ERR_FS_NOT_DIRECTORY errors (#4791)
    * Fix: mod_dav_svn's SVNUseUTF8 had no effect in some setups (r1844882)
    * Fix crash in mod_http2 (#4782)

  - Other tool improvements and bugfixes:
    * svndumpfilter: Clarify error messages by including node path (r1845261)

  - Bindings bugfixes:
    * JavaHL: Fix crash in client code when using external diff (r1845408)

 Developer-visible changes:
  - General:
    * Fix build on systems without python in $PATH (r1845555)

  - API changes:
    (none)