Multiple files can be added. Files ending in '.zip' will be searched
for 'xl.meta' files. Wildcards are accepted: 'testdir/*.txt' will compress
all files in testdir ending with '.txt', directories can be wildcards
as well. 'testdir/*/*.txt' will match 'testdir/subdir/b.txt', double stars
means full recursive. 'testdir/**/xl.meta' will search for all xl.meta
recursively.

FLAGS:
  {{range .VisibleFlags}}{{.}}
  {{end}}
`