scan for tarfiles in CACHE_DIR, remember what Subdirectory a tar was found in, set the GCF_FLAG on GRFs loaded from there, and hide those in the NewGRF GUI
Makefile*
bin/*
!bin/data/chars.grf
!bin/data/openttdd.grf
!bin/data/openttdw.grf
!bin/data/opntitle.grf
!bin/scenario/README
!bin/scripts*
config.*
objs/*
src/rev.cpp