Doc fixes.
Doc fixes.

(svn_fs_dir_subpool, svn_fs_file_subpool): Renamed from
svn_dir_subpool, svn_file_subpool.

(svn_fs_begin_txn): Let the caller specify a pool for TXN to live in.
(svn_fs_txn_subpool): New function.

(svn_fs_add_dir, svn_fs_replace_dir, svn_fs_add_file,
svn_fs_replace_file): New POOL argument.

Add persistent transaction interface.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion