Always at least log devWarnings.
Added methods debuglogResult and devWarningResult.

Lowering the barriers to sensible logging - these methods are
key in avoiding the "too much trouble" syndrome.
Add some logging to sinful typevar methods.

These super-mutation-oriented methods should enthusiastically
communicate what they are doing, especially when they encounter
anything unexpected. None of this work should be taken as an
endorsement of any of the worked-upon code.
Cleanup in isHKSubType0.

Making the mechanisms more apparent. Renamed to isHKSubType,
because there is no other.
Merge pull request #2196 from paulp/pr/logging-and-typevars

Logging little understood maneuverings during type inference