CHKZIP: check whether a file is a compressed archive

CHKZIP check whether file is a compressed archive

chkzip checks whether the passed file has one of the following
extensions: gz, zip, tar, tgz, tar.gz. If it does, chkzip
attempts to unpack the archive into a temporary location,
which is platform-dependent.

Usage:
[result, tmpFile] = chkzip(fileName)

fileName: file to be checked
result: number of files unpacked from compressed file,
or 0 if file extension was not recognized
tmpFile: full path to first extracted file if
unpacking was performed, otherwise returns
original filename

See also: GZIP, ZIP, TAR