James Turner : this patch

James Turner : this patch
- updates how filtering is done on the various FGPositioned query functions - both spatial and ident-based.
- updates the KLN-89b / DCLGPS code to use FGPositioned for all Navaid/Airport queries.

me:
Add few include directives in globals.cxx to avoid such MSVC warning messages :
deletion of pointer to incomplete type 'FGAirportList'; no destructor called
deletion of pointer to incomplete type 'FGNavList'; no destructor called
deletion of pointer to incomplete type 'FGTACANList'; no destructor called
deletion of pointer to incomplete type 'FGFixList'; no destructor called