Replace the obsolete race check from GiveUnitCrateAction.
Fixed drop-zone units
Merge pull request #5974 from pchote/cratefix

Fix unit collection crates and drop-zone maps.
Adds the RequiresPrerequisites field into ProvidesCustomPrerequisite and all the logic behind it.
Fix aircraft losing selection outside the map borders

Fixes #5651
Merge pull request #5965 from WolfGaming/CustomPrereqChange

Adds the RequiresPrerequisites field into ProvidesCustomPrerequisite
Merge pull request #5967 from obrakmann/fix5651

Fix aircraft losing selection outside the map borders
Fixes gem mine desert palette.
Merge pull request #5987 from reaperrr/gem-mine-palette

Fixes gem mine desert palette
Fix frozen actors being targetable under shroud. Fixes #5979, #5978.
Merge pull request #5989 from pchote/frozen-target-fix

Fix frozen actors being targetable under shroud.
Fix scripted paradrops.
Fix old-lua paradrop too.
Merge pull request #5988 from pchote/shellmap-paradrop

Fix scripted paradrops.
Merge the RA aircraft queues. Closes #5961.
Fix mouse event filtering in BackgroundWidget.
Allow ImageWidget to filter mouse events.
Fix mouseover filtering in cloned widgets.
Hide invalid hotkey from button tooltips.
Move TD production widgets into the RA project.