SI-7436 Varargs awareness for super param aliasing.

Don't consider a super class parameter accessor to be
an alias if it is a repeated. Parameter aliases are used
to avoid retaining redundant fields in the subclass; but
that optimization is out of the question here.
SI-6811 Deprecate scala.util.parsing.json
Merge pull request #2576 from retronym/ticket/7436

SI-7436 Varargs awareness for super param aliasing.
Merge pull request #2581 from soc/SI-6811-json

SI-6811 Deprecate scala.util.parsing.json
Partest redirects stderr to log file

Some scalac output is on stderr, and it's useful to see that
in the log file, especially for debugging.

Adds a line filter for logs, specified as "filter: pattern"
in the test source.

Test alignments:

Deprecations which do not pertain to the system under test
are corrected in the obvious way.

When testing deprecated API, suppress warnings by deprecating
the Test object.

Check files are updated with useful true warnings, instead of
running under -nowarn.

Language feature imports as required, instead of running under -language.

Language feature not required, such as casual use of postfix.

Heed useful warning.

Ignore broken warnings. (Rarely, -nowarn.)

Debug output from the test required an update.