Add support for extracing from non seekable stream

[ArnaudDebaene]

It is already possible to create a ZIP through streaming (with ZipOutputStream or ZipFile.Save(Stream).

However, it is not possible to unzip and stream the decompressed content from a non-seekable zip (ZipInputStream seeks into the input). This would be a nice addition (SharpZipLib already supports it).

Thanks!

[VanCoding]

I think this is an important feature, since unzipping from a HTTP request does not seem to be a rare requirement to me.