Fixed bugs:

• Issue #175: (define a 'b 'c) isn't valid form
• Issue #176: thread-pool-wait-all! hangs if one of the threads is terminated.
• Nested ellipsis was not resolved properly on R7RS syntax-rules
• thread-pool-task-running? raised an error.

Improvements:

• Building on FreeBSD uses gc-threaded if both gc and gc-threaded are found.
• Testing script detects timeout.
• Following the latest version of match.