Add-ons client

• Fixed: using the up or down arrow keys in small-screen mode returned to the title screen (issue #6485).
• Add-on passwords that are not stored in the `_server.pbl` can now be stored in the same credentials file as multiplayer passwords (PR #6543).
  

Campaigns

• Delfadors Memoirs[list]
• S11: Finding Chantal will now share her sides vision with the player, as originally intended.
• S14: Smoother appearance of enemies and added dialogue (#6176).
  

• Descent into Darkness[list]
• S08: Prevent Spectral Servant from picking up the book (issue #6576).
  

• Northern Rebirth[list]
• S05a_01: Solve units getting stuck in the wall before the spider chamber (issue #6607).
  

• Sceptre of Fire[list]
• Fixed Thursagan's Arcanister advancement being "lost" after dismounting a minecart.
• Improvements and spelling corrections to the English prose text (PR #6177).
• S9: Allow Grypon Riders to complete the scenario (issue #6332)
  

• Son of the Black Eye[list]
• Improvements and spelling corrections to the English prose text (PR #6166).
  

• The Rise of Wesnoth[list]
• S22: Fixed the possibility of a misplaced dialogue when a bridge was broken (issue #6376).
  

• Under the Burning Suns[list]
• S08: Kromph and the Dust devil now trigger a critical event (issue #6211).
  

• World Conquest[list]
• Updated the modding instructions, helping add-on authors add extra factions etc.
  

Editor

• Add documentation for the magenta D and special terrain overlays (PR #6460).
• Added some missing terrain groupings (issue #6643)
  

Multiplayer

• Fixed updating add-ons when joining a game that requires a new version (issue #6383).
• Add a `/clear` command for the lobby-chat window.
  

Packaging

• flatpak: update freedesktop runtime version to 21.08 (issue #6497).
  

Terrain

• Better transition for Swamp to Icy Cobbles (PR #6491).
• New graphics variations for icy and rocky terrains.
• The help browser adds special notes for castles and healing terrains (PR #6461).
  

Translations

• Updated translations: British English, Bulgarian, Chinese (Simplified), Czech, French, Italian, Japanese, Portuguese (Brazil), Russian
• Fixed the stats for Spanish being overwritten by the stats for Spanish (Latin American).
  

Units

• Saurian sprites cleanup (PR #6450).
• Various small sprite updates for sea serpents and swamp lizards (PR #6452).
  

User interface

• Mark the Plan Unit Advance mod as MP-only so it doesn't show up as available for campaigns.
  

Miscellaneous and Bug Fixes

• wmlscope can now report about calls to deprecated macros when using the `--unresolved` switch.
• wmlxgettexts old behavior of processing files in the order theyre given on the command line can be selected with the `--no-sort-by-file` option (PR #6586).
• Fixed a crash with "laststrike" (firststrike given to the opponent) weapon specials (issue #6575).
• Fixed a crash with locally-edited add-ons that had neither `_server.pbl` nor `_info.cfg` (issue #6389).
• Added more unit tests for weapon specials.
• Resolve crash on systems using musl implementation of libc (issue #6603)
• The `--stringfreeze` (`-Z`) command line flag has been removed from wmllint.
• The checks for the old special notes system have been removed from wmllint; the `notecheck off`, `notecheck on` and `match with ` magic comments no longer have any effect.
• Resolved title screen flashing during the loading screen (issue #2395)
• Fixed erratic keyboard and mouse scroll speed (issue #3607)
• wmllint automatically removes the obsolete lines `{SOUND:SLOW}` and `{SOUND:POISON}`