Fix for #1629, adds BOM to CSV export

[jliit]

Adds BOM to CSV export

The exported CSV-file is missing a byte order mark (BOM). This causes Excel to misinterpret the file and gets the encoding wrong. This PR adds a BOM to the beginning of the CSV-file.

Fixes #1629

Type of change

Please delete options that are not relevant.

• [ x] Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• [ x] My code follows the style guidelines of this project
• [ x] I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• [ x] My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• [ x] New and existing unit tests pass locally with my changes