Let's address some of the Spreadsheet exporter limitations in one go

• In addition of positions (Export location (x,y) option for CSV files #543) we should match the GEXF exporter and propose also colors, size with normalization option
• Implement csv export to use right locale. use comma instead of point in decimals #2072
• Implement Progress API so there is a meaningful progress bar while exporting
• Make it cancellable

In addition, we should standardize how dynamic attributes are exported and follow-up with additional tickets if needed. We should offer both

1. The full export of TimeSet and TimeMap -> reimporting them should be seamless
2. The static transformation using the Estimator