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

syntax: regexp

^objs/
^bin(-server)?/
^Makefile(.am)?$
\.swp$
^src/rev\.cpp$
^config\.(log|cache|cache\.source\.list)$