Change subtest to auto-note at the beginning of the test

Fix t/subtest/*.t to work with new auto-note
Fix outergroup test in t/subtest/predicate.t
Fix Test::Builder::Tester::complaint to not output double-spaced $wanted
Indent the subtest note with the subtest.

Discussed in #290.
Log the subtest note change.
Merge pull request #364 from schwern/subtest_note_at_start

Subtest note at start