- rework PropComparator.adapted() to be PropComparator.adapt_to_entity(),
passes in AliasedInsp and allows more flexibility.
- rework the AliasedClass/AliasedInsp relationship so that AliasedInsp has
all state and functionality.  AliasedClass is just a facade.
[ticket:2756]
turn this requirement back down as the simpler serialize works better now