Basic type struct inheritanace seems broken but:
- one was never used (PlayerID)
- the other (TileID) works almost the same without being a registered GType.
We lose the ability to make a true property with it but accessors are still
available to C users.
About header name, it just has to be defined once for the namespace as CCode
tag and that's enough, no need to sed around anymore.
By the way the definition of DATADIR which was stealing a hack.vapi slot
goes to a new file called -config and is declared as extern there which is
sufficient to be overridden by a -D at C compile time.