Cleaned up globstar code.
Fixed output formatting regression.
Made `run failed` use config.data_folder.
Test loaders and `run` harness keep tests sorted.

The system-testing rig relies on this for tests which make sure
history-related features like `run passed` are working. Also keeps
the tests in human-friendly order on OSes which don't sort their
listdir() output.
Improved CLI help text.

Fixed a parsing ambiguity in arg strings like `yuno run -h`
(regressed in #15).

Closes #21.
Merge branch 'issue21' into development
Better tools for system tests.

1. The system_test.py driver uses either output or the run log from the
Yuno under test, depending on the first line of the test file. Use
mode=output for the output and mode=log for the log. Using run logs
makes the tests less brittle against changes which affect the console
output but don't change what happens.

2. No more buffering in system_test.py. Test results reported as the
tests are running.

3. Fixed a path bug in mock_compiler.
More/updated fixtures for the test driver.
Added system tests.
Added test for 'run files'.
Test driver arguments pass through to Yuno.

(To the Yuno testing Yuno, not the Yuno being tested.)

To run tests:
> system_tests.py run <whatever> --diff --etc

To see results:
> system_tests.py show <whatever>
Tests for double-digit arguments to `run check`.
Tests for `run all` and `run phase .. check ..`.
Adds basic pre-test setup capability.

Driver test files can now set the contents of whatever data files
the test will read. Used to test commands like `run passed` which
depend on preexisting state.

General setup/teardown not supported. (Yet?)
Added tests for `run passed`, `run failed`, etc.

These tests depend on setup/teardown capability for log files
and require that their lines to be sorted.
Test driver sanity check.

This test rig isn't guaranteed to catch a bug where Yuno stops detecting
failures. Adds _canary, which contains a test that fails on purpose to
make sure the rig is working.
Added tests for `run suite`.
Tests for `show`.

Also added .log files not picked up before.
system_tests.py: rm log files after running test.
Converted system tests to YAML.