#41 CountMobs uses aafNumSlots_t as arg type

[Jim Trainor]

{ImplAAF,AAF}Header::CountMobs() both take an
aafNumSlots_t* as there only argument.

Obviously, aafNumSlots_t is not the intended type. It
should be aafUInt32.

It needs to be corrected in the dodo file, AAF.h must be
regenerated, and ImplAAFHeader files fixed.