Modification to enable producing consistent binary output

[ziembla]

Enabling consistent binary output by taking creation time from the metadata (if set) and:

1. using ZipInfo structure with that date for in-memory zipping

2. setting temporary files' modification time to that date with file-based zipping.

For more info see issue #494.

Usage:

from datetime import datetime
import xlsxwriter
import zipfile

options, properties = {}, {}
options = {'in_memory': True}
properties = {'created':  datetime(2017, 12, 31, 23, 59, 58)}
# properties = {'created':  datetime.now().date()}

path = 'demo.xlsx'

with xlsxwriter.Workbook(path, options) as workbook:
    if properties:
        workbook.set_properties(properties)
    worksheet = workbook.add_worksheet()
    worksheet.write('A1', 'abc')

with zipfile.ZipFile(path, 'r') as archive:
    for info in sorted(archive.infolist(), key=lambda i: i.filename):
        print("{} {}".format(datetime(*info.date_time).strftime("%Y-%m-%d %H:%M:%S"), info.filename))

[jmcnamara]

Merged. Thanks.

[ziembla]

The pleasure is mine :-)