three quotes on export

[davidnegreira]

When in run de program:
go run main.go testdata/testfile.xlsx

I get the following result:

"""Foo""";"""Bar"""
"""Baz """;"""Quuk"""

I'm newbie in go but reading the code I see in line 45:

vals = append(vals, fmt.Sprintf("%q", str))

the %q add quotes but go cw.Write(vals) add quotes too so the result is a lot of quotes 😄

golang writer.go line 89