update csv parser

• at least one timestamp_column is required (I think I already added this)
• headlines_to_exclude should be a string:
  • it's a comma separated list of integers indicating the line numbers (0-based) of the headlines to exclude
  • if it is only one number n: the first n lines should be excluded
• encoding
  • default: "utf-8"
  • there must also be an endpoint to fetch allowed encodings, maybe this could be a hard coded list instead of a table (but a table is also fine)
• header option:
  • it should be possible to use the header names for the datastreams
  • suggestion:
    • header_line: int, indicating the (0-based) line number of the header
    • use_header: boolean, indicating, that the header names should be used