Truncate long types in error messages

Fixes #542.

String representations of types in error messages are now cut off after 100 characters.
for test baselines we shoudl not be truncating.  LIke with TypeWriter, we want the full text so that if something changes here unexpectedly, we know about it.  With truncation, something may change and it coudl get missed if it was in teh truncated region.

Only for user visible features should we truncate.