Use names more like the other names in open_info.

For open_info, use names based on the names in other lists.

Also, in comments, indicate what the three count 'em three tables are
used for, and clean up the type/subtype table.

(cherry picked from commit ffa377b22f1b686b1cd0908a8b19cda13c556c39)

Conflicts:
	wiretap/file_access.c

Change-Id: I9af1ec8a8e00c6e07130fc43f06a9a6bbbd6497a
Reviewed-on: https://code.wireshark.org/review/4601
Reviewed-by: Guy Harris <guy@alum.mit.edu>