Special class designed to parse a Tar archive VERY FAST.
This class is not a general Tar archive solution because
it does not accomodate TarBuffer, or blocking. It does not
allow you to read the entries either. This would not be
difficult to add in a subclass.
The real purpose of this class is that there are folks out
there who wish to parse an ENORMOUS tar archive, and maybe
only want to know the filenames, or they wish to locate the
offset of a particular entry so that can process that entry
with special code.