editor: Fix a benign loop-variable-inside-closure issue

The getter is accessed exactly once, at call time.
The setter is stored, and invoked later on losing focus, but we pass a
bogus one anyway, so there is no issue.
filesystem: Fix benign use of loop variable in closure

This closure never outlives a single loop iteration.
LevelUpCrateAction: fix loop variable in closure bug

This was a real bug -- if there were multiple recipients, we'd apply the
levels N times to the last recipient rather than once to each.
PrimaryBuilding: Fix benign loop variable in closure hazard

This never outlived a single loop iteration.
WithMuzzleFlash: fix loop variable in closure hazard

This fixes a real bug -- if the actor had multiple armaments, we'd end
up placing the muzzle flashes all based on the offsets of the last one.
DomainIndex: Fix benign loop variable in closure hazard

This never outlived a single iteration of the neighbors loop.
Merge pull request #6704 from chrisforbes/closure-hazards

Closure hazards -- Fixes #6703