SharpCompress can now be used on machines with big endian architecture
such as powerpc. All byte conversions now run through Mono's
DataConverter (or a portable version for builds that don't allow unsafe
code) instead of BitConverter, as BitConverter's behavior depends on the
host cpu.
Some RARs with recovery records contain Protect Headers, I've added
support for parsing them so that RARs containing them can be read,
instead of an invalid-header exception being thrown. Parsing logic taken
from unrar reference source.
So that when working with ArchiveFactory, you can cast the opened
archive to IWritableArchive for accessing AddEntry, RemoveEntry and
SaveTo methods without having to know what type of archive is opened
underhood. Also moved extension methods from AbstractWritableArchive to
this new interface. Also added GZipArchive to ArchiveFactory.Create as
it is one of the 3 writable archive types (zip, tar, gzip), not sure why
it was omitted.
