On the fsfs-format7 branch:  Switch the representation uniquifier from
string to integers.  This is the first place where a transaction ID is
no longer used in its string format.

This is part of the "numerical IDs" patch series.

* subversion/include/svn_error_codes.h
  (SVN_ERR_FS_MALFORMED_TXN_ID): declare new error code

* subversion/libsvn_fs_fs/id.h
  (svn_fs_fs__id_part_t): document txn-id-specific behavior
  (svn_fs_fs__id_txn_parse,
   svn_fs_fs__id_txn_unparse): declare new API functions

* subversion/libsvn_fs_fs/id.c
  (txn_id_parse): new parser utility
  (svn_fs_fs__id_txn_parse,
   svn_fs_fs__id_txn_unparse): implement new API functions

* subversion/libsvn_fs_fs/fs.h
  (representation_t): the uniquifier is now a struct of ints

* subversion/libsvn_fs_fs/fs_fs.c
  (svn_fs_fs__noderev_same_rep_key,
   svn_fs_fs__rep_copy): update and simplify

* subversion/libsvn_fs_fs/low_level.c
  (svn_fs_fs__parse_representation,
   svn_fs_fs__unparse_representation): convert uniquifier <-> string

* subversion/libsvn_fs_fs/temp_serializer.c
  (serialize_representation,
   deserialize_representation): update and simplify

* subversion/libsvn_fs_fs/transaction.c
  (set_uniquifier): convert txn id string -> id part

* subversion/tests/cmdline/svntest/main.py

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1454671 13f79535-47bb-0310-9956-ffa450edef68