SI-7349 SI-7358 SI-7409 Par-Test checks and balances

A failing scalacheck test generates a test failure instead of allowing the build to succeed.
The failure log is added to the transcript.

Updates Scalacheck to 1.10.1 and invokes it using the
test-interface API. This obviates kludgy output checking for result
status.

Also, Partest testnum field width is sensitive to total tests.

Allow the hyphens to line up on a column within the output
for a test category or "kind".

Users are notified when check files are updated, and also when the compiler crashes instead of updating their check files.

Supersedes https://github.com/scala/scala/pull/2418

Review by @soc @adriaanm @retronym