[Gtkradiant] [Bug 800] New: add "ARCHIVE" API major, cleanup "VFS" major

[gtkradiant@zerowing.idsoftware.com]

http://zerowing.idsoftware.com/bugzilla/show_bug.cgi?id=800

           Summary: add "ARCHIVE" API major, cleanup "VFS" major
           Product: GtkRadiant
           Version: 1.3
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: editor
        AssignedTo: ttimo@idsoftware.com
        ReportedBy: ttimo@idsoftware.com


One important element is that we need to read inside both .wad and .pak files
A new "ARCHIVE" API major needs to be introduced, to access archive formats.
"pk3" "pak" "wad".
The code is already present in the various vfspk3 / vfspak / vfswad
implementations. Need to be abstracted behind an API (probably with a pure
virtual class to abstract the archive object)