Fix a few problems that cause Quicklisp testing failures.
Modify the TEST-OP for system INFERIOR-SHELL so that it invokes FIVEAM:RUN! to run tests.
Stop using package FIVEAM in test.lisp. That no longer works because both the FIVEAM and INFERIOR-SHELL packages define symbol !. Instead import the needed symbols.
Also, replace (return 1) in test.lisp with (false). Using return causes test OR to fail on my Linux system.