Add Application class

[bartosz-bear]

Add Application class.

[fzumstein]

What is your primary use case for this? E.g. closing the whole application?

[bartosz-bear]

Yes, that was the use I had in mind. Sometimes you run several commands in a script and the application remains open at the very end.

[fzumstein]

seems to make most sense as attribute of the Workbook object, e.g.:

>>> wb = Workbook()
>>> wb.application.quit()