Add multistream support to BZip2

[piksel]

Fixes #413. Fixes #162.

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[Numpsy]

(fixes #413 rather than 276?)

[piksel]

Gah. Github! Instead of using the number I actually typed, it auto-completed to the first search result that started with the number (413).

[Numpsy]

Not sure if this would be considered a real issue or not, but in case:

Does the usage of the Length property on the baseStream have any ramifications on the supported types of input stream?

Example: Say that I have a Zip file that contains a BZip2 file. With the current code I appear to be able to open a BZip2InputStream on the stream that is returned from ZipFile.GetInputStream and read the data from it, but with this change I get

System.NotSupportedException : InflaterInputStream Length is not supported

I'm not sure off hand is BZip2InputStream is inteded to support such streams though? (might possibly also happen if you tried it with a network stream or some such as well)

[philippk80]

In which release this will be available?

[piksel]

This will probably be in the next release. I have been super busy and neglected this unfortunately. Hopefully I will get time this weekend to fix current issues.

[piksel]

@Numpsy I made suggestions that should make it compatible with non-seekable streams. It will not access Stream.Length if multistream is not enabled, and it defaults to enable it only if the input stream supports seeking.