Ignores UnicodePathExtra if forced encoding is specified

[stakira]

• It may be surprising, but probably due to the history of Windows, it is not unusual to encounter zip files compressed with wrong unicode path info.
• My program provides a UI for users to preview decoded paths and choose a proper encoding before extracting. However, UnicodePathExtra always overriding specified encoding makes this impossible for some files.
• Forced encoding doesn't seem to be used anywhere, other than shadowing Default. That basically makes the two fields equivalent. Shouldn't it override UnicodePathExtra? Anyway, I think this is the intended behavior, instead of the current one.

[adamhathcock]

Seems valid to me. Can't say how all these cases will affect things