[Dev] Data Model API changes

[Andi Vajda]

I just made the following Data Model API changes and, hopefully, fixed all the
code affected:

  - Item's __init__() constructor is no longer called when items are loaded
    from the repository or loaded through loadPack(). The protected
    _fillItem() method is called instead. This method can be used to
    distinguish between programmatic creation and repository loading. The
    constructor is only called when an item is created programmatically (or
    loaded through Katie's format as it uses the regular programmatic API)
    I fixed all Item constructors and removed the ones doing nothing.

  - All Kinds, except for //Schema/Model/Item need to have at least one
    superKind. Until Katie implements this defaulting behaviour in
    DomainSchemaLoader, you need to ensure this manually. I changed all new
    format schema files to specify this default superKind.
    If I missed one you should be getting an exception about a missing
    superKind giving you the repository path to the kind in question.

I tested Chandler's zaobao, calendar, contacts, repository viewer parcels,
fixed bugs (due to my changes) in agents and all 'seems' to be fine.

Andi..