Remove deprecated >type metadata in zone definitions

[Laupetin]

Previously it has been possible to specify a type for a target in a zone definition via:

>type,fastfile
>type,ipak
>type,iwd

In the process of #286 this has been replaced by specifying obj containers like this:

>iwd,myiwd
>ipak,myipak

This allows obj containers to be created alongside a fastfile in one target.
Due to this, it is no longer necessary to have a type metadata.

For backwards compatibility the type property currently does the same thing as specifying the respective obj container with the name of the target.
It does log a deprecation warning however and will be removed in the future!