Add-ons client

• The `forum_auth` attribute now allows authenticating with your forum credentials, as well as no longer requiring the `passphrase` or `email` attributes be populated in the `_server.pbl`. (PR #5866)

Campaigns

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

• Northern Rebirth
  • S05a_01:
    • Solve units getting stuck in the wall before the spider chamber (issue #6607)
    • Enhance dialogue between Tallin and Abhai (issue #6608)

• Sceptre of Fire
  • Fixed Thursagan's Arcanister advancement being "lost" after dismounting a minecart (PR #6484).
  • Improvements and spelling corrections to the English prose text (PR #6177).

Lua API

• New `wesnoth.interface.add_overlay_text` function allows placing arbitrary floating text anywhere on the screen - like `[print]` but with more options (PR #5837).

Terrain

• New palisades terrain (^Eqp) and general fence terrain macros cleanup
• Rubble pile overlay terrain now connects with adjacent rubble piles
• Replace old-style terrain macros (PR #6606)

Translations

• Updated translations: British English, Czech, French, Italian

User interface

• Map labels are scaled by zoom (PR #6604).
• Revamped the Game Load dialog.

Miscellaneous and Bug Fixes

• Reduced the size of Isar's Cross map background images.
• Resolve crash on systems using musl implementation of libc (issue #6603).
• Refactoring of the C++ GUI2 event dispatcher.
• Refactoring of the `display` class' theme initialization.
• Fixed a crash with "laststrike" (firststrike given to the opponent) weapon specials (issue #6575).
• Added more unit tests for weapon specials.