1.0.0: Stable algorithm API

This first release refactors the io.streams.compress.Algorithm interface into an abstract base class, stabilizing the algorithm API.

• Made Algorithm implement the lang.Value interface, adding a string
  representation showing algorithm details
  (@thekid)
• Added Algorithm::level() which will return the fastest, default and
  strongest levels supported for the predefined Compression::DEFAULT,
  Compression::FASTEST and Compression::STRONGEST.
  (@thekid)
• Changed Algorithm::create() to accept either predefined constants for
  compression level or the level directly.
  (@thekid)