Fix comparing the column cs-coll and encodings in as-text mode.

This makes it less confusing for a Lisp hacker,
because a Lisp byte need not be an MySQL byte, but an octet is;
and a Lisp string is very different from a MySQL string, which is octets.

Add two utilities. Export assert-equal-helper from qtest.

The qmynd wire-protocol implementation was eagerly loading up the whole
content of a MySQL packet as a sequence of unsigned-bytes in memory, only to
then read from a stream built on-top of that sequence.

The new wire-packet implementation is a transparent stream where the next
packet's chunk is crossed transparently from within read-my-byte and
read-my-sequence calls, resulting in only fetching the data we need at any
time and bypassing all the stream to sequence of bytes to stream again in
the parsing of the data.

In passing, we also fix the handling of data as text.

Tests ran against this code show it about twice as fast as the previous
coding in best cases, and when disabling compression. There's now an option
to disable it at connection time (default to disable), because it's
unexpected to see compression offering any gain on a "local" connection
anyway, even more when using salza and chipz.

The sense of the signed bit in the type stream was reversed

Conflicts:
	src/common/conditions.lisp
	src/wire-protocol/basic-types.lisp

Conflicts:
	src/mysql-protocol/handshake.lisp
	src/wire-protocol/compressed-protocol.lisp

Use FLEXI-STREAMS:WITH-INPUT-FROM-SEQUENCE and
FLEXI-STREAMS:WITH-OUTPUT-TO-SEQUENCE where appropriate.

Convert the old function into the default implementation.
Add an abstraction-breaking implementation for FLEXI-STREAMS::VECTOR-INPUT-STREAM.

Add default implementation.

Use WITH-ACCESSORS when breaking the flexi-streams abstraction for the
FLEXI-STREAMS::VECTOR-INPUT-STREAM specialization.