Suggestion: Expose 'history-file' option from type-coverage

[paazmaya]

There is an option to specify a json file, for storing total sum of the coverage, in type-coverage.

Please expose that option.

[paazmaya]

Perhaps there even could be a plot chart in the resulting report, in case there are existing history?

[alexcanessa]

@paazmaya fancy giving it a try?

[kevinbarabash]

Is the intent of this option to store a top-level summary or are people looking for it to include coverage numbers for each file?