Fix double quote parsing error

[scootermon]

indexOf returns -1 when not found, which is a truthy value. This results in quotes getting stripped from every single line, which then causes an issue if the previously quoted string contained a colon.

Fixes #326

[jens-maus]

Please add test cases accordingly to get this PR accepted/integrated..

[jens-maus]

Thanks for integrating a test unit for this PR! However, what about using the exact ics string from the corresponding issue #326 in your unit test? IMHO it would be more precise to use the exact same ics to verify that #326 is really fixed.

[scootermon]

That's fair, I updated the test to match the example provided in the issue.