improved output for failed tapes of automated tape tests

improved output for failed tapes of automated tape tests

Failed tapes in automated tape tests (like "autotest <level set>") are
now separated into the following three cases:

- "BROKEN"     for newer tapes with "solution tape flag" set
- "UNSOLVABLE" for newer tapes with "solution tape flag" NOT set
- "FAILED"     for older tapes that do not have a "solution tape flag"

That way, it is easier to see if a failed tape is broken or unsolvable
"by design" (or too old to tell).