See README.unittests for information on how to run
the tests.  [ticket:970]

us a 2.5-frozen copy of unittest so we're insulated from unittest changes.

- Importing testenv has no side effects- explicit functions provide similar behavior to the old immediate behavior of testbase
- testing.db has the configured db
- Fixed up the perf/* scripts

- changed the various "literal" generation functions to use an anonymous
bind parameter.  not much changes here except their labels now look
like ":param_1", ":param_2" instead of ":literal"
- from_obj keyword argument to select() can be a scalar or a list.

means their lengths are dialect-dependent.  So on oracle a label
that gets truncated to 30 chars will go out to 63 characters
on postgres.  Also, the true labelname is always attached as the
accessor on the parent Selectable so theres no need to be aware
of the genrerated label names [ticket:512].
- ResultProxy column targeting is greatly simplified, and relies
upon the ANSICompiler's column_labels map to translate the built-in
label on a _ColumnClause (which is now considered to be a unique
identifier of that column) to the label which was generated at compile
time.
- still need to put a baseline of ColumnClause targeting for
ResultProxy objects that originated from a textual query.

so that exit code is propigated