Added flag `manualHeroVisit` flag to town building. If this flag is set,
then building will only be activated on click and will not give its
effect on hero recrutiment, hero visit, or new day.
This allows implementing changes to Mana Vortex from HotA
- Removed 'version' field from serialize() method
- Handler classes - Binary(De)Serializer now have 'version' field
- Serialization versioning now uses named enum
Save compatibility with 1.4.X saves should be intact