Zipmerge merges the content of many zip files, without decompressing and
recompressing the data.

Usage:

    zipmerge [-o out.zip] a.zip b.zip ...

By default, zipmerge appends the content of the second and subsequent zip
files to the first, rewriting the first in place. If the -o option is given,
zipmerge creates a new output file containing the content of all the zip
files, without modifying any of the source zip files.