Not mentioned here, but turning on debug mode also affects which units,
and therefore which units' traits, are shown in help.
Having looked back into the history while wondering why it was done this way
in e9603e6e01, back then we needed a fix that could be backported to 1.14,
so couldn't add a new attribute to [unit_type].
This diff fixes some glitches found that way and tells wmllint to ignore
various edge cases. A few cannot_use_message=NONE instances are removed,
as this simplifies the check and zookeeper says it's safe.
...for temporarily (for the duration of an event) clearing fog from
specific locations. Requires a helper unit, so also added a separate
dir for these kind of fake units in the units directory.
