Improved defects4j test command: support for external test suites; generate usage message from POD.
Improved defects4j test command: support for external test suites; generate usage message from POD.

rjust/defects4j,rjust/defects4j,jose/defects4j,jose/defects4j,rjust/defects4j,jose/defects4j,jose/defects4j,rjust/defects4j