Continue to format other files after error

[nevans]

When one file has an parse error, I would prefer that formatting continues for all of the other files that have no issue (after printing the error message). There should be a command line flag to enable or disable this behavior. My preference is to continue by default, but fail-fast by default (i.e. the current behavior) would be fine too.

[elia]

@nevans that works for me:

• I think stopping by default would be less surprising
• it should save up alle the error objects and exit with ≠ 0 if any error occurred
• errors should be shown at the end printing them on $stderr

Any chance you could try to send a PR for that?

[elia]

Upon further thinking I think the option can be named --no-fail-fast and also accept --fail-fast which would be on by default.

This is tangentially related to #17