CSV export: add UTF-8 BOM header.
When exporting a poll to CSV, no BOM character is written. Most applications can properly detect the required encoding, but some do not, and might find it helpful to be able to read a BOM character.
When exporting a poll to CSV, no BOM character is written. Most applications can properly detect the required encoding, but some do not, and might find it helpful to be able to read a BOM character.