[tex-live] install-tl from mirrored archive

[Karl Berry]

After tonight's run, the network directory (.../tlnet/2008) will contain
a functional version of the installer: the install-tl and install-tl.bat
scripts and support code in the tlpkg/ subdir.

Therefore, those who have a complete mirror of the network directory can
simply run "install-tl" and it will find the packages in the archive/
subdir.

This also means you can burn a copy of the complete 2008/ dir to a DVD
without changing anything and be able to install from it.

The previously available unpacked install-tl/ subdirectory is now gone,
since its only purpose was to make running the installer convenient.
Now it is more convenient.

Thanks to Norbert and Manuel for suggesting it.  Hope it helps.

Karl