introduce a new `test-run-complete` condition, and signal it when test
runs are complete.

This serves as an integration/extensibility point for other systems.

In my case, I'm going to have my continuous integration server listen
for this condition and process the test results, something like:

```lisp
(handler-bind ((lisp-unit:test-run-complete
                 #'(lambda (trc)
                     (process (lisp-unit:results trc)))))
  (asdf:test-system :foo))
```

refs #3
support test output using the test anything protocol

Converts a test-result object into TAP format. Two new functions:
 * `write-tap`
 * `write-tap-to-file`

To manage the indentation levels TAP wants, this uses
[pprint-logical-block] and heavily uses the [~I] format directive,
which is shorthand for [pprint-indent].  This gets a little tricky
because indentation levels only take effect after a newline.

[pprint-logical-block]: http://www.lispworks.com/documentation/HyperSpec/Body/m_ppr_lo.htm
[~I]: http://www.lispworks.com/documentation/HyperSpec/Body/22_cec.htm
[pprint-indent]: http://www.lispworks.com/documentation/HyperSpec/Body/f_ppr_in.htm

refs #3
enable print-pretty for TAP results
remove extraneous hyphen
Merge pull request #10 from AccelerationNet/tap

Tap output based off existing tap branch
Merge pull request #9 from AccelerationNet/master

new *keep-passing-asserts* flag to restrict memory usage
Optionally signal results.
Count passed assertions and only store details for failed assertions.
Add an optional stream argument to all print and output functions.
Warn on missing tests to remove and continue on.

Do no collect the removed names, the collected list wasn't used.
Warn on missing tags to remove and continue on.
record the run time of the test
print out test duration, in seconds
Merge pull request #12 from AccelerationNet/tap-with-test-times

Tap with test times
Correct the macro expansion assertion to number GENSYMS from 1.

Improve the comparison of the expanded forms.
Merge branch 'tap'

Conflicts:
	lisp-unit.lisp
Update the README for version 0.9.4.

Cover the new TAP features.
Signal a type-error if anything besides a symbol is used for a test name.
Replace assert-function with a generic function assert-result.

Specialize on the type of assertion. This better facilitates extensions.
Replace assert-class function with generic function record-failure.

Better facilitates extensions.