Include baselined errors as notes option

[DetachHead]

This would be useful when invoked from an IDE, not so much from the cli.

• for a cli alternative see #93

What if it said "baseline" instead of "note"?

demo.py:1:1: baseline: bad code  [bad-code]

Related #117

[DetachHead]

going to rename #109 instead of using this separate issue

[KotlinIsland]

#109 is more broad with several features,