Creating ZIP archives in Tcl
============================

  Rev 0.12: Added code to create directories (thx, Wojciech Kocjan)
  Rev 0.11: Added ?force? arg to bypass re-compression
  Rev 0.10: Initial release


Zipper is a package to create ZIP archives with a few simple commands:

    zipper::initialize $fd
    	initialize things to start writing zip file entries

    zipper::addentry name contents ?date? ?force?
    	add one entry, modification date defaults to [clock seconds]

    zipper::adddirectory name ?date? ?force?
    	add directory entry, modification date defaults to [clock seconds]

    zipper::finalize
    	write trailing table of contents, returns file descriptor

Example:

    package require zipper
    zipper::initialize [open try.zip w]
    zipper::addentry dir/file.txt "some data to store"
    close [zipper::finalize]

If the "zlib" package is available, it will be used to to compress the
data when possible and to calculate proper CRC-32 checksums.  Otherwise,
the output file will contain uncompressed data and zero checksums.