Improve feedback for Holmake.

Theorems proved with `fast_proof` are now regarded as cheated. The use of other oracle theorems is identified, though not marked as cheating.

Copy script output in multibuild when just 1 job running

When multiple scripts are going at once, the whirling single character
is all that can fit, but when there is just one job, we now see the last
line of its output as it runs.

Make multibuild spot "CHEAT" msgs from thy build

Then it can print a green CHEAT verdict for the theory as a
whole (contrasting with OK). Should also look into detection of failed
proofs that get accepted in absence of --qof flag.

Make parallel Holmake's output prettier

When a process fails, a chunk of its output up to the failure point is
output to the main screen. Also, a process that is killed because of a
general desire to give up (a failure elsewhere and no -k option, say),
now gets a red M-KILLED ("monitor killed") report.