Switch off clang format for the Windows include files in the picoquic sockets header, in order to avoid reordering bugs.

Formats source code with clang-format and adds clangformat target

Run `make clangformat` to format all the source code again.

Adds support for using a quic context as server/client

Before these changes, a context could either be a serer or a client.
With these changes, a context can be both.

Removes `#include "getopt.h"` as the functionality is provided by glibc

Added support for HTTP/0.9 tag in GET commands, and added corresponding test cases in the HTTP/0.9 server test.

Added a unit test to check that an HRR is correctly sent when the initial client hello does contain the correct initial share. Fixed a bug in the processing of the client hello.

Fixed the spurious retransmission bug and the bad acknowledgements bug. Added test case for spurious retransmit.

Added transport parameter test case that mimics options chosen by Quant. No changes in protocol code.

Added a test to check for absence a retransmission in a "silent" connection. Fixed a bug introduced when checking for already acked stream frames.

all server messages are prefixed with the initial connection ID.

stream is reset or if the data was already acked.

Wrote a stop sending unit test. Then, verified that the stop sending command actually works, and fixed bugs.

Added a non crypto random generator, for use when crypto randomness is not critical. This avoid exposing the state of the crypt random generator, thus prevents key leakage.