Don't hardcode the drush filename blacklist
Avoid '--invoke is an unrecognized option' error when Drush6 receives a backend request from a prior version of Drush.
This fixes #7.  Use array_merge_recursive to combine metadata in outputformat process() function instead of array += operator, which can cause sections of the metadata to be lost. This was breaking drush_format in some instances, which broke the outputformat topic (e.g. for csv)
If a Drush command returns a string value, then print it, even if the command does not define an outputformat record in its command definition.
Missed adjusting drupal-directory command in #24
filesystemTest was failing, because it used drush dl drush, and there are no longer any published drush releases on drupal.org
Missed adjusting sql-connect command in #24
Missed adjusting user-login command in #24
Update README.md

Required PHP Version is corrected as 5.3.3+.
Merge pull request #30 from pc-wurm/patch-1

Update README.md
README.txt has changed to README.md; update various references to match.
#6: Remove key-value and string topic text html files; these were left over from preliminary work that were committed by mistake, and made no sense in context.
Add a table of Drush versions to README.md
Update README.md

Reword to 'version'
#8: If a field's human-readable name differs from its machine name, then show both in the help text output
#8: Insure that cache-get and config-get help only shows output formats that are usable by these commands.
Fix #28. config-import and config-edit commands updated for D8 changes.
Get rid of --stdin in config-set and use '-' as the indicator, like cache-set.
Avoid a minor warning in config test.
Insure that Drush will set an error status code from sql-query if the query fails for any reason.  Fixes #34.