support CSV output

[phiwuu]

As a user of the lobster HTML report I want to filter the report so that I can see all items with issues.

Possible Solution

Instead of, or additionally to refactoring the HTML output to support large data sets (see #32) it might be better to add a feature to generate the report in csv or excel format. This way users can easily filter their reports according to their needs with their favorite csv tool, and we don't need to foresee all their filtering use cases.

[phiwuu]

It is not clear which kind of columns should appear in a *.csv file. The lobster file contains nested information. Think about the "location" of an element. Should all properties of the location be added to individual columns of a *.csv file? I will close this ticket. We can open it again once the stakeholder request is clear.