don't unify the two types of properties inside a RevertableProperty
don't unify the two types of properties inside a RevertableProperty

While it was ok to have RevertableProperty HasInfo even when
the undo property did not have any info, and it would be ok to have
RevertableProperty Debian even when the undo property targeted a wider
set of OS's, type-level resource conflict detection needs to keep
the two straight, as in RevertableProperty (Port 80 + Debian) Debian

Without that, reverting a web server property and also including another
property that uses port 80 would fail to compile, since the type system
would not know if reverting RevertableProperty (Port 80 + Debian) continued
using the resource or not.

The downside is the need to write RevertableProperty Debian Debian
... Perhaps I'll add a type alias to avoid that or something.

ArchiveTeam/glowing-computing-machine