Prevent already failed objectives from being marked as completed

The same change was not and must not be done in the reverse case. It
should be and is possible to mark an already completed objective as
failed.

Consider a case where a player is supposed to capture, but not destroy,
a building.  He captures it, the objective is complete.  However, later
in the game that building gets destroyed. In this case, the objective
should be changed to failed.
Add more functions for objectives management to Lua API
Update existing maps
Add a chat tab to end-game window

Fixes #6422
Remove stats button from end-game dialog in mission-type maps

Still available for skirmish games and replays.
Merge pull request #6494 from obrakmann/objectives-fine-tuning

Objectives fine-tuning
Remove obsolete —upgrade-map-v5 and --setings-value commands.
Merge pull request #6473 from obrakmann/fix6422

Add chat tab to end-game dialog
Make the TS Construction Yard selectable

Increasing the size of the selection box to make the Construction Yard selectable.
Polishing/normalizing new GUI
Fixed training camp map

Removed unused traits,
fixed prerequisites
and fixed two typos.
Made dog buildable at fort lonestar
Merge pull request #6518 from s1ww/player_gui

Polishing/normalizing new GUI
Added IUtilityCommand and move default commands into Mods.Common.
Merge pull request #6516 from LipkeGu/patch-1

Make the TS Construction Yard selectable
Revert "Polishing/normalizing new GUI"

This reverts commit 5020c7a73ed2352656a7cab4ccfb621854f6582b.
Merge pull request #6527 from pchote/revert-6518

Revert "Polishing/normalizing new GUI"
Merge pull request #6493 from pchote/utility-commands

Move utility commands into the mod assemblies.
Merge pull request #6519 from abcdefg30/trainingcamp

Repaired Trainingcamp map
Add Mod.Common Graphics

Moved Graphics to Mod.Common