Summary output

[Zeckie]

Currently output ends with a summary like:
Success: no issues found in 321 source files
or
Found 5 errors in 4 files (checked 321 source files)

Would it be useful to include some baseline specific details, such as

• How many errors were ignored due to the baseline
• How many errors are in the baseline, but no longer in the code
• How many different types of error (in the baseline / code)

[KotlinIsland]

How many errors are in the baseline, but no longer in the code

This should mostly be covered by auto-baseline, which feels like the most relevant to a normal mypy invokation. The other suggestions feel like they would fit better in some baseline specific commands, like --baseline-report or something.

Take a look at #93

[Zeckie]

How many errors were ignored due to the baseline

I was thinking of something like:

Found 5 errors in 4 files (checked 321 source files). Ignored 1234 errors in 54 files due to baseline file.
or
Success: no issues found in 321 source files. Ignored 1234 errors in 54 files due to baseline file.