On the fsfs-format7 branch: Implement a packed string table object.
This code is WIP, neither tested nor documented.

* subversion/libsvn_fs_fs/string_table.h
  new file
  (string_table_builder_t,
   string_table_t): declare new internal API data types
  (svn_fs_fs__string_table_builder_create,
   svn_fs_fs__string_table_builder_add,
   svn_fs_fs__string_table_create,
   svn_fs_fs__string_table_get,
   svn_fs_fs__string_table_copy_string): declare new internal API

* subversion/libsvn_fs_fs/string_table.c
  new file
  (MAX_DATA_SIZE,
   MAX_SHORT_STRING_LEN,
   TABLE_SHIFT,
   MAX_STRINGS_PER_TABLE,
   LONG_STRING_MASK,
   STRING_INDEX_MASK): define new constants
  (builder_string_t,
   builder_table_t,
   string_table_builder_t,
   string_header_t,
   string_sub_table_t,
   string_table_t): define new data types
  (add_table,
   balance,
   match_length,
   insert_string,
   create_table,
   table_copy_string): implement new utility functions
  (svn_fs_fs__string_table_builder_create,
   svn_fs_fs__string_table_builder_add,
   svn_fs_fs__string_table_create,
   svn_fs_fs__string_table_get,
   svn_fs_fs__string_table_copy_string): implement new internal API


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1451163 13f79535-47bb-0310-9956-ffa450edef68