Enhancements:

  - Add a technical white paper with a detailed description and specification
    of Ouinet's architecture, components and protocols.
  - Update the request/response flow diagram to reflect current Ouinet
    architecture.
  - Cleanup cache code to remove unused abstractions.

Bugfixes:

  - Fix responses with an empty body loaded from signed HTTP storage missing
    the block signature in the last chunk header.

This fixes block signatures missing from the last chunk of empty responses
loaded from signed HTTP storage (and sent to other clients).

Unit test added as well.

Otherwise the Proxy mechanism will fail in this mode for a lack of
`X-Ouinet-Private: True` in requests.

This updates the request/response flow diagram to match current Ouinet
architecture.

Building up the distributed cache.

They are not the names of system components.

Also use "URI response" instead of "URI data" and remove pending URI
descriptor.

To reinforce the fact that the injector sends a request to the origin, signs
the response and sends it back to the client.

These are no longer part of the architecture since clients are the only ones
publishing entries to the distributed cache index.

Also descriptors have been replaced by HTTP signatures.

As we have only one class deriving from it

Features:

  - Automatic, periodic garbage collection of local cache entries older than
    the maximum cache age.
  - Ability to purge the local cache via client API and front-end.
  - Approximate local cache size can be retrieved via the client API and
    front-end.

Enhancements:

  - Unify client endpoints to `127.0.0.1:8077` (HTTP proxy) and
    `127.0.0.1:8078` (front-end) by default and enable both by default.
  - Update readme to remove obsolete information and better help testing.
  - More efficient URI swarm name computations.
  - Use newer OpenSSL library.
  - Use a non-dummy version number in the client API, and have proper release
    notes. `;)`

Bugfixes:

  - Avoid issues with BitTorrent bootstrap nodes resolving to an IPv6 address
    first.
  - Avoid the agent from furiously retrying when there is no fresh mechanism
    available.
  - Other fixes for Android and asynchronous operations, timeouts and
    cancellations.

This unifies endpoints used by the client in the different current scenarios:
standalone binary, Docker container, Android library.

Now the default HTTP proxy endpoint is `127.0.0.1:8077`, and the default
front-end endpoint is `127.0.0.1.:8078`, with both enabled by default.

The reason for `127.0.0.1` and not something less prone to clashes like
`127.7.2.1` (as we do in the injector) is that the client is expected to run
on many platforms (while we can assume GNU/Linux for the injector), and not
all of them support binding to addresses in `127.0.0.0/8` other than
`127.0.0.1` (e.g. macOS and other BSD-based systems).  Thus it becomes more
reasonable to choose a less crowded port (8077 and the following one in this
case).

Documentation and other references in code and other files have been updated
as well.

This contains many updates to the readme file for removing obsolete
information and better help test the technology.