All save compatibility checks targeting 1.4 saves have now been removed.
Saves from 1.5 can still be loaded in 1.6
Implemeted few TODO's in serialization that were postponed to avoid
breaking save compatibility in MP for 1.5.X releases.
Fixed missed case for loading black market object from 1.5 saves
marketModes are now generated in runtime and are not a member of
IMarket. Was not a bad change, but towns load buildings before town type
is randomized, leading to case where market modes are not actually known
when building is added to town (like random towns with market built)
Since altar requires CArtifactSet for work, IMarket will now always
contain it, but it will only be accessible if market supports altar
mode.
