On the fsfs-format7 branch: indexing code cleanup.  Shorten some of the
struct names, fix a few typos and improve commentary.

* subversion/libsvn_fs_fs/index.c
  (l2_index_page_table_entry_t): rename to ...
  (l2p_page_table_entry_t): ... this
  (l2p_index_header_t): rename to ...
  (l2p_header_t): ... this and update it
  (l2p_index_page_t): rename to ...
  (l2p_page_t): ... this
  (l2_proto_index_entry_t): rename to ...
  (l2p_proto_entry_t): ... this
  (p2l_index_header_t): rename to ...
  (p2l_header_t): ... this
  (write_entry_to_proto_index,
   svn_fs_fs__l2p_proto_index_add_revision,
   svn_fs_fs__l2p_proto_index_add_entry,
   svn_fs_fs__l2p_index_create,
   get_l2p_header,
   get_l2p_page,
   l2p_index_lookup,
   l2p_proto_index_lookup,
   svn_fs_fs__l2p_get_max_ids,
   get_p2l_header,
   svn_fs_fs__p2l_index_lookup): update users


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1444668 13f79535-47bb-0310-9956-ffa450edef68