Fix server freeze on client absence.
Remove duplicated IronCurtainable rules.
Add a UnitUpgradeManager trait.

This introduces support for timed upgrades, starting with crate buffs.
Fix cloak upgrade expiration.
Reimplement iron curtain as a generic stat upgrade.
Add the invulnerability crate to RA.
Add a GrantUpgradeWarhead and initial TS EMP implementation.
Replace RemoveOnConditions with KillsSelf.

Upgrades offer more flexibility than prerequisites.
Detonate demo trucks when they are iron-curtained.
Rename UnitUpgradeCrateAction to GrantUpgradeCrateAction.
Expose upgrades to map scripts.
Remove the now-redundant ScriptInvulnerable trait.
Mods.Common Widgets

Moved over Widgets that don't require a bunch of things to move.
Scroll Panel Sound

Adds sound to Up, Down, and Thumb Button
Harvester now autoharvest when produced
Merge pull request #6634 from abcdefg30/autoharvest

Let harvesters autoharvest when produced
Merge pull request #6623 from steelphase-forks/bleed-ScrollPanelSound

Scroll Panel Sound
Extended IMove for Enter logic
Extend Enter activity class for (re)usability in enter/exit/dock logic
Add support for generic tooltip names.