constructs would fail if the bind were constructed with a callable,
rather than a direct value.  This prevented ORM expressions
from being rendered with the "literal_binds" compiler flag.

such as "literal binds" into a CAST expression.
- Fixed bug whereby binary type would fail in some cases
if used with a "test" dialect, such as a DefaultDialect or other
dialect with no DBAPI.
- Fixed bug where "literal binds" wouldn't work with a bound parameter
that's a binary type.  A similar, but different, issue is fixed
in 0.8.

backwards compatibility.  A note about backslashing escapes is added.
Because the Text() construct now supports bind params better, the example
given in the code raises an exception now, so that should cover us.
The exception itself has been enhanced to include the key name of the
bound param.  We're backporting this to 0.8 but 0.8 doesn't have the
text->bind behavior that raises.

have been modified, such that the COLLATE operator is now of lower
precedence than the comparison operators.  This has the effect that
a COLLATE applied to a comparison will not render parenthesis
around the comparison, which is not parsed by backends such as
MSSQL.  The change is backwards incompatible for those setups that
were working around the issue by applying :meth:`.Operators.collate`
to an individual element of the comparison expression,
rather than the comparison expression as a whole. [ticket:2879]

more flexible ways to set up bound parameters and return types;
in particular, a :func:`.text` can now be turned into a full
FROM-object, embeddable in other statements as an alias or CTE
using the new method :meth:`.TextClause.columns`.
[ticket:2877]

- move out tests, dialect specific out of compiler, compiler tests use new API,
legacy API tests in test_selecatble
- add support for adaptation of ForUpdateArg, alias support in compilers

with conjunctions, e.g.
``None`` :func:`.expression.null` :func:`.expression.true`
:func:`.expression.false`, including consistency in rendering NULL
in conjunctions, "short-circuiting" of :func:`.and_` and :func:`.or_`
expressions which contain boolean constants, and rendering of
boolean constants and expressions as compared to "1" or "0" for backends
that don't feature ``true``/``false`` constants. [ticket:2804]